In PHP an extended class is always dependent on a single base class,that is, multiple inheritance is not supported. Classes are extended using the keyword 'extends'.
CONSTRUCTOR : PHP allows developers to declare constructor methods for classes. Classes which have a constructor method call this method on each newly-created object, so it is suitable for any initialization that the object may need before it is used. DESTRUCTORS : PHP 5 introduces a destructor concept similar to that of other object-oriented languages, such as C++. The destructor method will be called as soon as all references to a particular object are removed or when the object is explicitly destroyed or in any order in shutdown sequence.
The header() function sends a raw HTTP header to a client.We can use herder()function for redirection of pages. It is important to notice that header() mustbe called before any actual output is seen.
The visibility of a property or method must be defined by prefixing the declaration with the keywords public, protected or private.
Class members declared public can be accessed everywhere.
Members declared protected can be accessed only within the class itself and by inheritedand parent classes.
Members declared as private may only be accessed by the class that defines the member.
echo $_SERVER['HTTP_USER_AGENT'].”\n\n”; $browser=get_browser(null,true); print_r($browser);
Everything is passed by value.
htmlentitiesis used to convert all applicable characters to HTML entities.It is used to stop the user from running malicious code in HTML.With use of htmlentities, user can't run the html tags like h2, p, script etc. It helps to prevent you fromXSS attack.
echo htmlentities($userData);
PHP function start with "functionfunction-name()".
PHP Function name must be start withcharacterand it acceptalphanumericand_.
In build functions arecase in-sensitive.
User build functions arecase sensitive.
We can pass upto 64 parameter as argument.
Anonymous functionare user defined function which have "no-name" and also called closures.
PHP supportvariable functions. Means when you can call a function using variable.
In same file OR under same class, same function name can't be created
func_num_args() function returns the number of parameters passed in.
With use virtual host and htaccess, you can create sub domain
Create an session in PHP.
Session data is stored in Server.
Session data have unique name.
Session unique key with domain name is stored in browser cookie.
Now, Browser keep the login with use of unique key(in cookie) and session data (stored in server side)
If you want to include special characters like spaces in the query string, you need to protect them by applying the urlencode() translation function. The script below shows how to use urlencode():
print(“”);
print("Please click the links below"."to submit comments about:");
$comment = 'I want to say: "It\'s a good site! :->"';
$comment = urlencode($comment);
print(“”.””.”It's an excellent site!”);
$comment = 'This visitor said: “It\'s an average site! “';
$comment = urlencode($comment);
print(“”.''.”It's an average site.”);
print(“”);
By default the PHP script takes 30secs to execute. This time is set in the php.ini file. This time can be increased by modifying the max_execution_time in seconds. The time must be changed keeping the environment of the server. This is because modifying the execution time will affect all the sites hosted by the server.Explain the purpose of output buffering in PHP.
Output buffering in PHP buffers a scripts output. This buffer can be edited before returning it to the client. Without output buffering, PHP sends data to the web server as soon as it is ready. Output buffering "send" cookies at any point in the script. Cookies donot have to be necessarily sent near the start of page. Output buffers are stackable and hence sending to output is by choice.How can we know the number of days between twogiven dates using PHP?
The start date and end date can be first found as shown below:
$date1= strotime($start_date);
$date2= strotime($end_date);
$date_diff = (($date1)- ($date2)) / (60*60*24)Write the statements that are used to connect PHP with MySQL
The statements that can be used to connect PHP wil MySQL is:
$conn = mysql_connect('localhost');
echo $conn;
?>
This statement gets the resource of the localhost. There are other different ways with which you can connect to the database and they are as follows:
mysql_connect('db.domain.com:33306','root','user');
mysql_connect('localhost:/tmp/mysql.sock');
mysql_connect('localhost','rasmus','foobar',
true,MYSQL_CLIENT_SSL|MYSQL_CLIENT_COMPRESS);
?>
How to use HTTP Headers inside PHP? Write the statement through which it can be added?
HTTP headers can be used in PHP by redirection which is written as
session_set_save_handler() sets the user-level session storage functions which are used for storing and retrieving data associated with a session. This is most useful when a storage method other than those supplied by PHP sessions is preferred. i.e. Storing the session data in a local database
sizeof($urarray) This function is an alias of count()
count($urarray)
A design pattern is a general reusable solution to a commonly occurring problem in software design.
The Singleton design pattern allows many parts of a program to share a single resource without having to work out the details of the sharing themselves
we will need to compile PHP with the GD library of image functions for this to work. GD and PHP may also require other libraries, depending on which image formats you want to work with
The PDF functions in PHP can create PDF files using the PDFlib library With version 6, PDFlib offers an object-oriented API for PHP 5 in addition to the function-oriented API for PHP 4. There is also the » Panda module. FPDF is a PHP class which allows to generate PDF files with pure PHP, that is to say without using the PDFlib library. F fromFPDF stands for Free: you may use it for any kind of usage and modify it to suit your needs. FPDF requires no extension (except zlib to activate compression and GD for GIF support) and works with PHP4 and PHP5
Responsive web design (RWD) is a web design approach aimed at crafting sites to provide an optimal viewing experience, easy navigation and reading with a minimum of scrolling, resizing and panning. across a wide range of devices (all mobiles, desktop, laptop, ipad etc)
Persistent cookie is a cookie which is permanently stored on user’s computer in a cookie file. They are used for tracking the user information of the users who are browsing from a very long time. They also have the drawbacks of being unsecure, asuser can see the cookies which are saved on the computer
Depend on Operating System
\023 is octal 23
\x23 is hex 23
MIME - Multi-purpose Internet Mail Extensions.
MIME types represents a standard way of classifying file types over Internet.
Web servers and browsers have a list of MIME types, which facilitates files transfer of the same type in the same way, irrespective of operating system they are working in. A MIME type has two parts: a type and a subtype. They are separated by a slash (/). MIME type for Microsoft Word files is application and the subtype is msword, i.e. application/msword.Explain how to execute a PHP script using command line.PHP script using command line can be executed using SAPI (Server Application programming Interface). Using SAPI Command Line Interface the PHP code can be passed to execute directly
MultipurposeInternetMailExtensions
WWW ability to recognize and handle files of different types is largely dependent onthe use of the MIME (Multipurpose Internet Mail Extensions) standard. The standardprovides for a system of registration of file types with information about the applications needed to process them
In MySQL, the default table type is MyISAM. Each MyISAM table is stored on disk in three files. The files have names that begin withthe table name and have an extension to indicate the file type. The '.frm’ file stores the table definition. The data file has a '.MYD’ (MYData) extension. The index file has a '.MYI’ (MYIndex) extension
When the original if was followed by : and then the code block without braces
You can encrypt a password with the following Mysql>SET PASSWORD=PASSWORD(“Password”); You can also use the MySQL PASSWORD() function to encrypt username and password. For example, INSERT into user (password, ...) VALUES (PASSWORD($password”)), ...);
Total 5 types of tables we can create 1. MyISAM 2. Heap 3. Merge 4. INNO DB 5. ISAM MyISAM is the default storage engine as of MySQL 3.23. When you fire the above create query MySQL will create a MyISAM table
whenever a user logs in track the IP, userID etc..and store it in a DB with a active flag while log out or sesion expire make it inactive. At any time by counting the no: of activerecords we can get the no: of visitors
By checking the session variable exist or not while loading th page. As the session will exist longer as till browser closes. The default behaviour for sessions is to keep a sessionopen indefinitely and only to expire a session when the browser is closed. This behaviour can be changed in the php.ini file by altering the line session.cookie_lifetime = 0 to a value in seconds. If you wanted the session to finish in 5 minutes you would set this to session.cookie_lifetime = 300 and restart your httpd server
default session time in PHP is 1440 seconds or 24 minutesDefault session save path id temporary folder /tmp
Using Disposition-Notification-To: in mailheader we can get read receipt.Add the possibility to define a read receipt when sending an email.It’s quite straightforward, just edit email.php, and add this at vars definitions:
var $readReceipt = null;
And then, at 'createHeader' function add:
if (!empty($this->readReceipt)) {
$this->__header .= 'Disposition-Notification-To: ' . $this->__formatAddress($this- >readReceipt) . $this->_newLine;
}
by using spl_autoload_register('autoloader::funtion');Like below
class autoloader{
public static function moduleautoloader($class){
$path = $_SERVER['DOCUMENT_ROOT'] . “/modules/{$class}.php”;
if (is_readable($path)) require $path;
}
public static function daoautoloader($class){
$path = $_SERVER['DOCUMENT_ROOT'] . “/dataobjects/{$class}.php”;
if (is_readable($path)) require $path;
}
public static function includesautoloader($class){
$path = $_SERVER['DOCUMENT_ROOT'] . “/includes/{$class}.php”;
if (is_readable($path)) require $path;
}
}
spl_autoload_register('autoloader::includesautoloader');
spl_autoload_register('autoloader::daoautoloader');
spl_autoload_register('autoloader::moduleautoloader');
Calculate the md5 hash of a string. The hash is a 32-characterhexadecimal number.I use it to generate keys which I use to identify users etc. If I add random no techniques to it the md5 generated now will be totally different for the same string I am using
Set char to occupy n bytes and it will take n bytes even if u r storing a value of n-m bytes Set varchar to occupy n bytes and it will take only the required space and will not use the n bytes eg. name char(15) will waste 10 bytes if we store 'romharshan’, if each char takes a byte eg. name varchar(15) will just use 5 bytes if we store 'romharshan’, if each chartakes a byte. rest 10 bytes will be free
Garbage Collection is an automated part of PHP , If the Garbage Collection process runs, it then analyzes any files in the /tmp for any session files that have not been accessed in a certain amount of time and physically deletes them. GarbageCollection process only runs in the default session save directory, which is /tmp. If you opt to save your sessions in a different directory, the Garbage Collection processwill ignore it. the Garbage Collection process does not differentiate between which sessions belong to whom when run. This is especially important note on shared web servers. If the process is run, it deletes ALL files that have not been accessed in the directory. There are 3 PHP.ini variables, which deal with the garbage collector: PHP ini value name default session.gc_maxlifetime 1440 seconds or 24 minutes session.gc_probability 1 session.gc_divisor 100
In PHP an extended class is always dependent on a single base class, that is, multipleinheritance is not supported. Classes are extended using the keyword 'extends’
stdClass__PHP_Incomplete_Class exception php_user_filter
By using setcookie(name, value, expire, path, domain); function we can set the cookie in php ; Set the cookies in past for destroy. like setcookie(“user”, “sonia”, time()+3600); for set the cookie setcookie(“user”, “”, time()-3600); for destroy or delete the cookies;
session_unregister- Unregister a global variable from the current sessionsession_unset - Free all session variables
session_id() returns the session id for the current session
Just run the PHP CLI (Command Line Interface) program and provide the PHP script file name as the command line argument. For example, “php myScript.php”, assuming “php” is the command to invoke the CLI program.Be aware that if your PHP script was written for the Web CGI interface, it may not execute properly in command line environment.
Once the Web server received the uploaded file, it will call the PHP script specified in the form action attribute to process them. This receiving PHP script can get the uploaded file information through the predefined array called $_FILES. Uploaded file information is organized in $_FILES as a two-dimensional array as:
$_FILES[$fieldName]['name']- The Original file name on the browser system. $_FILES[$fieldName]['type'] - The file type determined by the browser. $_FILES[$fieldName]['size'] - The Number of bytes of the file content. $_FILES[$fieldName]['tmp_name'] - The temporary filename of the file in which the uploaded file was stored on the server. $_FILES[$fieldName]['error'] - The error code associated with this file upload.The $fieldName is the name used in the
urlencode() returns the URL encoded version of the given string. URL coding converts special characters into % signs followed by two hex digits. For example: urlencode(“10.00%”) will return “10.00%′′. URL encoded strings are safe to be used as part of URLs. urldecode() returns the URL decoded version of the given string.String urlencode(str) - Returns the URL encoded version of the input string. String values to be used in URL query string need to be URL encoded. In the URL encodedversion: Alphanumeric characters are maintained as is.Space characters are converted to “+” characters. Other non-alphanumeric characters are converted “%” followed by two hex digits representing the converted character. string urldecode(str) - Returns the original string of the input URL encoded string. For example: $discount =”10.00%”; $url = “http://domain.com/submit.php?disc=”.urlencode($discount); echo $url;You will get “http://domain.com/submit.php?disc=10.00%??
Via define() directive, like define (“MYCONSTANT”, 100);
By using date_default_timezone_get anddate_default_timezone_set function on PHP 5.1.0
// Set the default timezone to Tokyo time:
date_default_timezone_set(’Asia/Tokyo’);
// Now generate the timestamp for that particular timezone, on Jan 1st, 2000
$stamp = mktime(8, 0, 0, 1, 1, 2000);
// Now set the timezone back to US/Eastern
date_default_timezone_set(’US/Eastern’);
// Output the date in a standard format (RFC1123), this will print:
// Fri, 31 Dec 1999 18:00:00 EST
echo '
', date(DATE_RFC1123, $stamp) ,’
'; ?>
$second = date(”s”);
Convert all applicable characters to HTML entitiesThis function is identical to htmlspecialchars() in all ways, except with htmlentities(), all characters which have HTML character entity equivalents are translated into these entities
Public: Public declared items can be accessed everywhere.Protected: Protected limits access to inherited and parent classes (and to the class that defines the item).
Private: Private limits visibility only to the class that defines the item.
Static: A static variable exists only in a local function scope, but it does not lose its value when program execution leaves this scope.
Final: Final keyword prevents child classes from overriding a method by prefixing the definition with final. If the class itself is being defined final then it cannot be extended.
Transient: A transient variable is a variable that may not be serialized.
Volatile: a variable that might be concurrently modified by multiple threads should be declared volatile. Variables declared to be volatile will not be optimizedby the compiler because their value can change at any time
Sometimes a function is best shared among a number of different classes. Such functions can be declared either as member functions of one class oras global functions. In either case they can be set to be friends of other classes, by using a friend specifier in the class that is admitting them. Such functions can use all attributes of the class which names them as a friend, as if they were themselvesmembers of that class. A friend declaration is essentially a prototype for a memberfunction, but instead of requiring an implementation with the name of that class attached by the double colon syntax, a global function or member function of another class provides the match
The action attribute determines where to send the form-data in the formsubmission
"method" attribute determines how to send the form-data into the server.There are two methods, get and post. The default method is get.This sends the form information by appending it on the URL.Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send
Associative arrays are arrays that use string keys is called associative arrays
This function is used to determine if a variable is set and is not NULL
It is used to generate random numbers.If called without the arguments it returns a pseudo-random integer between 0 and getrandmax(). If you want a random number between 6 and 12 (inclusive), for example, use rand(6, 12).This function does not generate cryptographically safe values, and should not be used forcryptographic uses. If you want a cryptographically secure value, consider using openssl_random_pseudo_bytes() instead
strlen() function used to find the length of a string
index.php is the default name of the home page in php based sites
exit() function is used to stop the execution of a page
The following code can be used for it, header("Location:index.php");
The header() function sends a raw HTTP header to a client browser.Remember that this function must be called before sending the actual out put.For example, You do not print any HTML element before using this function
Object orientation is a software/Web development methodology that is based on the modeling a real world system.An object is the core concept involved in the object orientation. An object is the copy of the real world enity.An object oriented model is a collection of objects and its inter-relationships
The date() function provides you with a means of retrieving the currentdate and time, applying the format integer parameters indicated in your script to the timestamp provided or the current local time if no timestamp is given. In simplified terms, passing a time parameter is optional - if you don't, the current timestamp will be used
To send email using PHP, you use the mail() function.This mail() function accepts 5 parameters as follows (the last 2 are optional). You need webserver, you can't send email from localhost. eg : mail($to,$subject,$message,$headers);
MD5 PHP implements the MD5 hash algorithm using the md5 function, eg : $encrypted_text = md5 ($msg); mcrypt_encrypt :- string mcrypt_encrypt ( string $cipher , string $key , string $data , string $mode [, string $iv ] ); Encrypts plaintext with given parameters
Html entities Convert all applicable characters to HTML entities This function is identical to htmlspecialchars() in all ways, except with htmlentities(), all characters which have HTML character entity equivalents are translated into these entities
session_id() function returns the session id for the current session
The enctype attribute determines how the form-data should be encodedwhen submitting it to the server. We need to set enctype as "multipart/form-data" when we are using a form for uploading files
Using define() directive, like define ("MYCONSTANT",150)
They are both variables. But $var is a variable with a fixed name. $$varis a variable who's name is stored in $var. For example, if $var contains "message", $$var is the same as $message
It is used for sort an array by key in reverse order
Unlink() deletes the given file from the file system
$filename = "/home/user/guest/newfile.txt";
$file = fopen( $filename, "w" );
if( $file == false )
{
echo ( "Error in opening new file" ); exit();
}
fwrite( $file, "This is a simple test\n" );
fclose( $file );
Syntax : array explode ( string $delimiter , string $string [, int $limit ] ); This function breaks a string into an array. Each of the array elements is a substring of string formed by splitting it on boundaries formed by the string delimiter.
1. mysql_fetch_row 2. mysql_fetch_array 3. mysql_fetch_objec 4. mysql_fetch_assoc
1. mysql_fetch_row. 2. mysql_fetch_array 3. mysql_fetch_object 4. mysql_fetch_assoc
It is a classic example of PHP’s variable variables. take the following example. $message = “Raghav”; $$message = “is a owner of https://sharag.wordpress.com/ “; $message is a simple PHP variable that we are used to. But the $$message is not avery familiar face. It creates a variable name $mizan with the value “is a moderator of PHPXperts.” assigned. break it like this${$message} => $mizanSometimes it is convenient to be able to have variable variable names. That is, a variable name which can be set and used dynamically
preg_match(”/^http://.+@(.+)$/”,’[email protected]’,$found);echo $found[1];
In php.ini file: set short_open_tag=on to make PHP support
When to use GET or POST The HTML 2.0 specification says, in section Form Submission (and the HTML 4.0 specification repeats this with minor stylistic changes): ->If the processing of a form is idempotent (i.e. it has no lasting observable effecton the state of the world), then the form method should be GET. Many database searches have no visible side-effects and make ideal applications of query forms. - ->If the service associated with the processing of a form has side effects (for example, modification of a database or subscription to a service), the method should be POST
When to use GET or POST The HTML 2.0 specification says, in section Form Submission (and the HTML 4.0 specification repeats this with minor stylistic changes): ->If the processing of a form is idempotent (i.e. it has no lasting observable effecton the state of the world), then the form method should be GET. Many database searches have no visible side-effects and make ideal applications of query forms. - ->If the service associated with the processing of a form has side effects (for example, modification of a database or subscription to a service), the method should be POST
strpos() is used to find the position of the first occurrence of a substring in a string
Read/Write. Creates a new file. Returns FALSE and an error if file already exists
The main idea behind this is to use Javascript submit() function in order to submit the form without explicitly clicking any submit button. You can attach the document.formname.submit() method to onclick, onchange events of different inputs and perform the form submission. youcan even built a timer function where you can automatically submit the form after xx seconds once the loading is done (can be seen in online test sites)
As of version 4.3.0, PHP supports a new SAPI type (Server Application Programming Interface) named CLI which means Command Line Interface. Just run the PHP CLI (Command Line Interface) program and provide the PHP script file name as the command line argument. For example, “php myScript.php”, assuming “php” is the command to invoke the CLI program. Be aware that if your PHP script was written for the Web CGI interface, it may not execute properly in command line environment
You can find these specific information in PHP Manual.
All of those are open source resource. Security of Linux is very very more than windows. Apache is a better server that IIS both in functionality and security. MySQL is world most popular open source database. PHP is more faster that asp or any other scripting language
Inserts HTML line breaks ( ) before all newlines in a string string nl2br (string); Returns string with ” inserted before all newlines. For example: echo nl2br(”god bless/n you”) will output “god blessyou” to your browser
One of the main advantages of OO programming is its ease of modification; objects can easily be modified and added to a system there by reducing maintenance costs. OO programming is also considered to be better at modeling the real world than is procedural programming. It allows for more complicated and flexible interactions. OO systems are also easier for non-technical personnel to understand and easier for them to participate in the maintenance and enhancement of a system because it appeals to natural human cognition patterns. For some systems, an OO approach can speed development time since many objects are standard across systems and can be reused. Components that manage dates, shipping, shopping carts, etc. can be purchased and easily modified for a specific system
The functions in this section perform encryption and decryption, andcompression and uncompression
Function Description printf() : Displays a formatted strings printf() : Saves a formatted string in a variable fprintf() : Prints a formatted string to a file number_format() : Formats numbers as strings
type: exif_imagetype() size: use getimagesize() width: use imagesx() height: use imagesy()
URL coding converts special characters into % signs followed by two hex digits. For example, urlencode("10.00%") will return "10.00%?urldocode is just opposite to urlencode
Apdex means Application Performance Index. It is standard method for reporting & comparing the performance of software. Purpose: Analyse the performance, user satisfaction & expectation then Convert into percentage. Formula Apdex = (Satisfied + Tolerating / 2) / Total Satisfied: Response time is less than or equal to T. Tolerated: Response time is more than T and (Less than OR Equal to 4T); Frustrated: Response time is greater than 4T. T: It is threshold time define by application owner. Example: https://docs.newrelic.com/docs/assets/apdex.pdf
New Relic is software as a service (SaaS) that monitors your Website and mobile applications(Android, iOS) in real-time that run in different environments like cloud, on-premise and hybrid. Following are few benefits of New Relic 1. Monitoring your website regularly. 2. Downtime Notification by email. 3. Custom Error recording and then report you in email & also can view in newrelicwebsite. 4. Key Transaction tracking: You will be able to see where your application is spending most of its time (e.g. inthe controller, model OR database). 5. External Service Call Recording (Webservices)
World Wide Web The number(eg 1,2,3,4,5....) that follows the "WWW" indicates that the data beingretrieved by the Web browser is gathering the information from a different Web server than the one that serves the typical "WWW" address. Web sites, especially dynamic Web sites, that handle large amounts of traffic oftenneed more than one server to accommodate the many requests they receive as one server often cannot handle the multitude of requests. Examples https://www1.pearsonvue.com/ https://www2.pearsonvue.com/ https://www3.pearsonvue.com/ https://www4.pearsonvue.com/ https://www5.pearsonvue.com/ https://www6.pearsonvue.com/ Here all above websites have same data
A static variable is defined within a function only the first time and its value can be modified during function calls as follows
CURL means Client URL Library curl is a command line tool for transferring files with URL syntax, supporting FTP, FTPS, HTTP, HTTPS, SCP, SFTP, TFTP, TELNET, DICT, LDAP, LDAPS and FILE. curl supports SSL certificates, HTTP POST, HTTP PUT, FTP uploading, HTTP form based upload, proxies, cookies, user+password authentication (Basic, Digest, NTLM, Negotiate, kerberos ¦), file transfer resume, proxy tunneling and a busload of other useful tricks. CURL allows you to connect and communicate to many different types of servers with many different types of protocols. libcurl currently supports the http, https, ftp, gopher, telnet, dict, file, and ldap protocols. libcurl also supports HTTPS certificates,HTTP POST, HTTP PUT, FTP uploading (this can also be done with PHP ™s ftp extension), HTTP form based upload, proxies, cookies, and user+password authentication
$postData = array(
"site" => "web technology experts notes",
"dailyuser" => "1000",
"location" => "India"
);
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "http://www.example.com");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);
$output = curl_exec($ch);
curl_close($ch);
echo $output;
$array = array('cakephp','zend'); sizeof($array); count($array);
$array = array('one','two'); echo serialize($array);//use unserialize for convert serialized string to array
$array = array('one','two'); echo json_encode($array); //use json_decode for decode
array_merge example
$array1 = array('one','two');
$array2 = array(1,2);
$result = array_merge($array1,$array2);
print_r($result);
array_combine example
$array1 = array('one','two');
$array2 = array(1,2);
$result = array_combine($array1,$array2);
print_r($result);
$array = array('cakephp','zend'); $string =implode(' and ',$array); echo $string;
$string="cakephp and zend"; $array =explode('and',$string); print_r($array);
count() is used to count all elements in an array, or something in an object
Eg : var $arr = array('apple', 'grape', 'lemon');
Both are used to split a string to array, the basic difference is that split() uses pattern for splitting and explode() uses a string. explode() is faster than split() as it does not match the string based on regular expression. Also split() is deprecated as of 5.3.0. So using of this function is discouraged
For finding length of string we use strlen() function and for array we use count() function
$a === $b TRUE if $a and $b have the same key/value pairs in the same order and of the same types
$_COOKIE is an associative array of variables sent to the current PHP script using the HTTP Cookies
$_ENV is an associative array of variables sent to the current PHP script via the environment method
$_FILES is an associative array composed of items sent to the current script via the HTTP POST method
$_SERVER is an array including information created by the web serversuch as paths, headers, and script locations
$GLOBALS is associative array including references to all variables which are currently defined in the global scope of the script
__sleep returns the array of all the variables that need to be saved, while __wakeup retrieves them
array_combine give an array by combining two arrays($keyArray, $valueArray) and both $keyArray & $valueArray must have same number of elements. $keyArrays become keys of returning Array, $valueArray become values of returning Arrays. array_merge gives an array by merging two array ($array1, $array2) and both can have different number of elements. $array1 and $array2 are added in returning array.
2 ways a) sizeof($urarray) This function is an alias of count() b) count($urarray)
Sort(), arsort(), asort(), ksort(), natsort(), natcasesort(), rsort(), usort(), array_multisort(), anduksort().
count() is used to count all elements in an array, or something in an object
in_array used to checks if a value exists in an array
Eg : var $arr = array('apple', 'grape', 'lemon');
There are two methods through which we can know the total number ofelements: sizeof($array_var) count($array_var)
1. You use static when you want to use a method / variable that is not tied to an instance. 2. When you want to persistent value throughout multiple call of function. 3. For singleton pattern, we use static method/variable. 4. it is very usefull for caching if a method will be called very often and do just the same thing. For example see below
protected function is_logged_in() {
static $logged_in = null;
if($logged_in != null) {
return $logged_in;
}
//Check shibboleth headers
if (!empty($_SERVER['HTTP_SHIB_IDENTITY_PROVIDER']) || !
empty($_SERVER['Shib-Identity-Provider'])) {
if (!empty($_SERVER[$this->core->dbconfig("shib_auth", self::SHIB_AUTH_CONFIG_UID)])) {
$logged_in = true;
return true;
}
}
$logged_in = false;
return false;
}
PHP can't read the hash portion of the URL index.php?page=group#birthday Here, PHP can not read the birthday There is some by which you can get this valueget the value by javascript and then set to cookie or pass in ajax. See Example var query = location.href.split('#'); [removed]s = 'hasValue=' + query[1];
A persistent cookie is a cookie which is stored in a cookie file permanently on the browser’s computer. By default, cookies are created as temporary cookies which stored only in the browser’s memory. When the browser is closed, temporary cookies will be erased. You should decide when to use temporary cookies and when to use persistent cookies based on their differences: *Temporary cookies can not be used for tracking long-term information. *Persistent cookies can be used for tracking long-term information. *Temporary cookies are safer because no programs other than the browser can access them. *Persistent cookies are less secure because users can open cookie files see the cookievalues.
eg : echo $_COOKIE["user"];
Setcookie ("sample", "ram", time()+3600);
Yes, it is possible by setting the cookie with a past expiration time.
A persistent cookie is permanently stored in a cookie file on the browser’s computer. By default, cookies are temporary and are erased if we close the browser
It is possible to propagate a session id via cookies or URL parameters
Cookie are stored in client side (e.g Browser) where as Session are stored in server side (tmp file of web server). Cookie can be added/update/delete from browser but session can't delete from browser. Session is depended on cookie. For example: When user login in website then session is created in webserver
The main difference between sessions and cookies is that sessions are stored on the server, and cookies are stored on the user’s computers in the text fileformat. Cookies can not hold multiple variables,But Session can hold multiple variables.We can set expiry for a cookie,The session only remains active as long as the browser is open.Users do not have access to the data you stored in Session,Since it is stored in the server.Session is mainly used for login/logout purpose while cookies using for user activity tracking
eg : echo $_COOKIE["user"];
Setcookie("sample", "ram", time()+3600);
A session is a logical object created by the PHP engine to allow you to preserve data across subsequent HTTP requests.There is only one session object available to your PHP scripts at any time. Data saved to the session by a script can be retrieved by the same script or another script when requested from the same visitor.Sessions are commonly used to store temporary data to allow multiple PHP pages to offer a complete functional transaction for the same visitor
session_destroy();
unset($_SESSION['object']);
The default session time in php is until closing of browser
The session_unregister() function unregister a global variable from the current session and the session_unset() function free all session variables
Sessions automatically ends when the PHP script finishs executing, but can be manually ended using the session_write_close().
The use of the function session_start() lets us activating a session
A session is a logical object enabling us to preserve temporary data across multiple PHP pages
$_SESSION['name'] = “tut2learn”
$_SESSION[’name’] = “RAGHAV”;
$_SESSION[’name’] = “RAGHAV”;
session_unregister — Unregister a global variable from the current session session_unset — Free all session variable
session_id() returns the session id for the current session
What you’re really asking is whether they know how to use session_start(). It either creates or resumes a session based on an identifier that is sent to the server via a GET or POST request or a cookie. The most common use case scenario on the web is when a website won’t let you comment or post without first prompting a login. How does it know whether you’re logged in? One way would be to place a cookie in the user’s browser; on every request the cookie is sent server-side, where PHP can be used to determine which information is sent back and displayed to the client. While session_start() saves session data in files by default, it is also possible to store sessions directly in the database.
echo $_SESSION['REMOTE_ADDR'];
Works in following Flow 1. Open website http://www.web-technology-experts-notes.in/ 2. Request send to server of http://www.web-technology-experts-notes.in/ 3. Call PHP Files. 4. PHP Scripts are loaded into memory and compiled into Zend opcode. 5. These opcodes are executed and the HTML generated. 6. Same HTML is send back to Browser.
In Zend Framework, bootstrapping is the process that loads your application. This includes, but is not limited to the Session. Any resources needed by your application to process the request (the dispatch) to the application is bootstrapped/loaded/initialized before the request is fulfilled, e.g. before the controller delegates any input to the model and creates a response that is send back to the client.
Dispatching is the process of taking the request object, Zend_Controller_Request_Abstract, extracting the module, controller, action name, and optional parameters contained in it, and then instantiating a controller and calling an action of that controller. If any of the module name, controller name, or action are not found, it will use default values for them. Zend_Controller_Dispatcher_Standard specifies index for each of the controller and action defaults and default for the module default value, but allows the developer to change the default values for each using the setDefaultController(), setDefaultAction(), and setDefaultModule() methods, respectively.
$_SERVER['HTTP_USER_AGENT']
By using $_SERVER['REMOTE_ADDR'], $_SERVER['HTTP_REFERER'] etc
By using $_SERVER['HTTP_USER_AGENT'] variable
Via define() directive, like define (“MYCONSTANT”, 100);
The output is displayed directly to the browser.
Abstract class: abstract classes are the class where one or more methods are abstract but not necessarily all method has to be abstract. Abstract methods are the methods, which are declare in its class but not define. The definition of those methods must be in its extending class.Interface: Interfaces are one type of class where all the methods are abstract. That means all the methods onlydeclared but not defined. All the methods must be define by its implemented class
Simple arithmetic: $date1 = date('Y-m-d’); $date2 = ’2006-07-01?; $days = (strtotime() - strtotime()) / (60 * 60 * 24); echo “Number of days since ’2006-07-01?: $days”;
PEAR is the next revolution in PHP. This repository is bringing higher level programming to PHP. PEAR is a framework and distribution system for reusablePHP components. It eases installation by bringing an automated wizard, and packingthe strength and experience of PHP users into a nicely organised OOP library. PEAR also provides a command-line interface that can be used to automatically install “packages” PEAR is short for “PHP Extension and Application Repository” and is pronounced just like the fruit. The purpose of PEAR is to provide: A structured library of open-sourced code for PHP users A system for code distribution and package maintenance A standard style for code written in PHPThe PHP Foundation Classes (PFC), The PHP Extension Community Library (PECL), A web site, mailing lists and download mirrors to support the PHP/PEAR communityPEAR is a community-driven project with the PEAR Group as the governing body. The project has been founded by Stig S. Bakken in 1999 and quite alot of people have joined the project since then
In general, a framework is a real or conceptual structure intended to serve as a support or guide for the building of something that expands the structure into something useful. Advantages : Consistent Programming Model Direct Support for Security Simplified Development Efforts Easy Application Deployment and Maintenance
Model-view-controller (MVC) is an architectural pattern used in software engineering. Successful use of the pattern isolates business logic from user interface considerations, resulting in an application where it is easier to modify either the visual appearance of the application or the underlying business rules without affecting the other. In MVC, the model represents the information (the data) of the application; the view corresponds to elements of the user interface such as text, checkbox items, and so forth; and the controller manages the communication of data and the business rules used to manipulate the data to and from the model. WHY ITS NEEDED IS 1 Modular separation of function 2 Easier to maintain 3 View-Controller separation means: A Tweaking design (HTML) without altering code B Web design staff can modify UIwithout understanding code
Using URL rewriting we can convert dynamic URl to static URL Static URLs are known to be better than Dynamic URLs because of a number of reasons 1. Static URLs typically Rank better in Search Engines. 2. Search Engines are known to index the content of dynamic pages a lot slower compared to static pages. 3. Static URLs are always more friendlier looking to the End Users. along with this we can use URL rewriting in adding variables [cookies] to the URL to handle the sessions
Magic Quotes is a process that automagically escapes ncoming data to the PHP script. It's preferred to code with magic quotes off and to instead escape the data at runtime, as needed. This feature has been DEPRECATED as of PHP 5.3.0 and REMOVED as of PHP 6.0.0. Relying on this feature is highly discouraged
parent::constructor(
$string="cakephp and zend"; echo ucwords($string);
This is the encoding used to send image or files via form, The data will be split into multiple parts and, one for each files plus one for the text of the form body that may be sent with them
The PHP Data Objects (PDO) extension defines a lightweight, consistent interface for accessing databases in PHP. It is a data-access abstraction layer, so no matter what database we use the function to issue queries and fetch data will be same. Using PDO drivers we can connect to database like DB2, Oracle, PostgreSQL etc
unset() is used to destroy a variable where as unlink() is used to destroy a file
We cannot change the value of a constant
Yes, it’s possible to integrate (Distributed) Component Object Model components ((D)COM) in PHP scripts which is provided as a framework
The use of the set_time_limit(int seconds) enables us to extend the execution time of a php script. The default limit is 30 seconds
The three basic classes of errors are notices (non-critical), warnings (serious errors) and fatal errors (critical errors)
Yes, we use the urlencode() function to be able to protect special characters
The function eregi_replace() is identical to the function ereg_replace() except that it ignores case distinction when matching alphabetic characters
for is expressed as follows: for (expr1; expr2; expr3) statement The first expression is executed once at the beginning. In each iteration, expr2 is evaluated. If it is TRUE, the loop continues and the statements inside for are executed. If it evaluates to FALSE, the execution of the loop ends. expr3 is tested at the end of each iteration. However, foreach provides an easy way to iterate over arrays and it is only used with arrays and objects
The string function strstr(string allString, string occ) returns part of allString from the first occurrence of occ to the end of allString. This function is case-sensitive. stristr() is identical to strstr() except that it is case insensitive
The boolean function isset determines if a variable is set and is not NULL
The function parse_ini_file() enables us to load in the ini file specified in filename, and returns the settings in it in an associative array
Exception::__toString gives the String representation of the exception
Exception::getMessage lets us getting the Exception message and Exception::getLine lets us getting the line in which the exception occurred
The goto statement can be placed to enable jumping inside the PHP program. The target is pointed by a label followed by a colon, and the instruction is specified as a goto statement followed by the desired target label
To be able to verify whether a PHP variable is an instantiated object of a certain class we use instanceof
!= means inequality (TRUE if $a is not equal to $b) and !== means non-identity (TRUE if $a is not identical to $b)
The first is the concatenation operator ('.’), which returns the concatenation of its right and left arguments. The second is ('.=’), which appends the argument on the right to the argument on the left
$a and $b: TRUE if both $a and $b are TRUE. $a & $b: Bits that are set in both $a and $b are set
The scope of a variable is the context within which it is defined. For the most part all PHP variables only have a single scope. This single scope spans included and required files as well.
We can change the maximum size of files to be uploaded by changing upload_max_filesize in php.ini
$_FILES['userfile’]['error’] contains the error code associated with theuploaded file
$_FILES['userfile’]['name’] represents the original name of the file on the client machine, $_FILES['userfile’]['tmp_name’] represents the temporary filename of the file stored on the server
No, a parent constructor have to be called explicitly as follows:parent::constructor($value)
In PHP, objects passed by value
:: is used to access static methods that do not require object initialization
$$var2 contains the value 10
The function func_num_args() is used to give the number of parameters passed into a functio
It is composed of three expressions: a condition, and two operands describing what instruction should be performed when the specified condition is true or false as follows: Expression_1 ? Expression_2 : Expression_3;
When the original if was followed by : and then the code block withoutbraces
The name of the output type have to be specified in parentheses before the variable which is to be cast as follows: * (int), (integer) - cast to integer * (bool), (boolean) - cast to boolean * (float), (double), (real) - cast to float * (string) - cast to string* (array) - cast to array * (object) - cast to object
“13” and 12 can be compared in PHP since it casts everything to the integer type
To be able to pass a variable by reference, we use an ampersand in front of it, as follows $var1 = &$var2
The define() directive lets us defining a constant as follows:define (“ACONSTANT”, 123);
The PHP-openssl extension provides several cryptographic operations including generation and verification of digital signatures
It is preferable to use crypt() which natively supports several hashing algorithms or the function hash() which supports more variants than crypt() rather than using the common hashing algorithms such as md5, sha1 or sha256 because they are conceived to be fast. hence, hashing passwords with these algorithms can vulnerability
A function returns a value using the instruction 'return $value;’
This feature is possible using the global keyword
To know the Image type use exif_imagetype () function To know the Image size use getimagesize () function To know the image width use imagesx () function To know the image height use imagesy() function
unlink() deletes the given file from the file system. unset() makes a variable undefined
URLencode returns a string in which all non-alphanumeric charactersexcept -_. have been replaced with a percent (%) sign followed by two hex digits and spaces encoded as plus (+) signs. It is encoded the same way that the posted data from a WWW form is encoded, that is the same way as inapplication/x-www-form-urlencoded media type. urldecode decodes any %## encoding in the given string.
By using date_default_timezone_get and
date_default_timezone_set function on PHP 5.1.0
// Discover what 8am in Tokyo relates to on the East Coast of the US
// Set the default timezone to Tokyo time:
date_default_timezone_set('Asia/Tokyo’);
// Now generate the timestamp for that particular timezone, on Jan 1st, 2000
$stamp = mktime(8, 0, 0, 1, 1, 2000);
// Now set the timezone back to US/Eastern
date_default_timezone_set('US/Eastern’);
// Output the date in a standard format (RFC1123), this will print:
// Fri, 31 Dec 1999 18:00:00 EST
echo '
’, date(DATE_RFC1123, $stamp) ,’
’;?>
$second = date(“s”);
Convert all applicable characters to HTML entitiesThis function is identical to htmlspecialchars() in all ways, exceptwith htmlentities(), all characters which have HTML character entityequivalents are translated into these entities
There are lots of tools available for asp to PHP conversion. you can search Google for that. the best one is available athttp://asp2php.naken.cc
strstr Returns part of string from the first occurrence of needle(sub string that we finding out ) to the end of string. $email= '[email protected]’; $domain = strstr($email, '@’); echo $domain; // prints @gmail.com here @ is the needle stristr is case-insensitive means able not able to diffrenciate between a and A
Sometimes a function is best shared among a number of differentclasses. Such functions can be declared either as member functions ofone class or as global functions. In either case they can be set to befriends of other classes, by using a friend specifier in the class thatis admitting them. Such functions can use all attributes of the classwhich names them as a friend, as if they were themselves members of thatclass. A friend declaration is essentially a prototype for a member function,but instead of requiring an implementation with the name of that classattached by the double colon syntax, a global function or memberfunction of another class provides the match.
There are lot of difference between procedure language and object oriented like below 1>Procedure language easy for new developer but complex to understand whole software as compare to object oriented model 2>In Procedure language it is difficult to use design pattern mvc , Singleton pattern etc but in OOP you we able to develop design pattern 3>IN OOP language we able to ree use code like Inheritance ,polymorphism etc but this type of thing not available in procedure language on that our Fonda use COPY and PASTE
Traditional programming has the following characteristics:Functions arewritten sequentially, so that a change in programming can affect any code that follows it. If a function is used multiple times in a system (i.e., a piece of code that manages the date), it is often simply cut and pasted into each program (i.e., a change log, order function, fulfillment system, etc). If a date change is needed (i.e., Y2K when the code needed to be changed to handle four numerical digits instead of two), all these pieces of code must be found, modified, and tested. Code(sequences of computer instructions) and data (information on which the instructions operates on) are kept separate. Multiple sets of code can access and modify one set of data. One set of code may rely on data in multiple places. Multiple sets of code and data are required to work together. Changes made to anyof the code sets and data sets can cause problems through out the system.Object-Oriented programming takes a radically different approach:Code and data are merged into one indivisible item - an object (the term “component” has also been used to describe an object.) An object is an abstraction of a set of real-world things (for example, an object may be created around “date”) The object would contain all information and functionality for that thing (A date object it may contain labels like January, February, Tuesday, Wednesday. It may contain functionality that manages leap years, determines if it is a business day or a holiday, etc., See Fig. 1). Ideally, information about a particular thing should reside in only one place in a system.The information within an object is encapsulated (or hidden) from the rest of the system. A system is composed of multiple objects (i.e., date function, reports, order processing, etc., See Fig 2). When one object needs information from another object, a request is sent asking for specific information. (for example, a report object may need to know what today’s date is and will send a request to the date object) These requests are called messages and each object has an interface that manages messages. OO programming languages include features such as “class”, “instance”, “inheritance”, and “polymorphism” that increase the power andflexibility of an object
Calculate the md5 hash of a string. The hash is a 32-characterhexadecimal number. I use it to generate keys which I use to identifyusers etc. If I add random no techniques to it the md5 generated nowwill be totally different for the same string I am using
Set char to occupy n bytes and it will take n bytes even if u r storing a value of n-m bytes Set varchar to occupy n bytes and it will take only the requiredspace and will not use the n bytes eg. name char(15) will waste 10 bytes if we store 'mizan’, if each char takes a byte eg. name varchar(15) will just use 5 bytes if we store 'mizan’, if each char takes a byte. rest 10 bytes will be free
In PHP an extended class is always dependent on a single base class,that is, multiple inheritance is supported by interfaces. Classes are extended using the keyword 'extends’.
Firstly, the the HTTP protocol specifies differing usages for the two methods. GET requests should always be idempotent on the server. This means that whereas one GET request might (rarely) change some state on the Server, twoor more identical requests will have no further effect. This is a theoretical point which is also good advice in practice. If a user hits “reload” on his/her browser, an identical request will be sent to the server, potentially resulting in two identical database or guestbook entries, counter increments, etc. Browsers may reload a GET URL automatically, particularly if cacheing is disabled (as is usually the case with CGI output), but will typically prompt the user before re-submitting a POST request. This means you’re far less likely to get inadvertently-repeated entries from POST. GET is (in theory) the preferred method for idempotent operations, such as querying a database, though it matters little if you’re using a form. There is a further practical constraint that many systems have built-in limits to the length of a GET request they can handle: when the total size of a request (URL+params) approaches or exceeds 1Kb, you are well-advised to use POST in anycase. I would prefer POST when I don’t want the status to be change when user resubmits. And GET when it does not matter
The normalization process involves getting our data to conform to three progressive normal forms, and a higher level of normalization cannot be achieved until the previous levels have been achieved (there are actually five normal forms,but the last two are mainly academic and will not be discussed).First Normal Form The First Normal Form (or 1NF) involves removal of redundant data from horizontal rows. We want to ensure that there is no duplication of data in a given row, and that every column stores the least amount of information possible (making the field atomic). Second Normal Form Where the First Normal Form deals with redundancy of data across a horizontal row, Second Normal Form (or 2NF) deals with redundancy of data in vertical columns. As stated earlier, the normal forms are progressive, so to achieve Second Normal Form, your tables must already be in First NormalForm.Third Normal Form I have a confession to make; I do not often use Third Normal Form. In Third Normal Form we are looking for data in our tables that is not fully dependent on the primary key, but dependent on another value in the table
quotation from the HTML 4.0 specification -> If the method is “get” - -, the user agent takes the value of action, appends a ? to it, then appends the form data set, encoded using the application/x-www-form-urlencoded content type. The user agent then traverses the link to this URI. In this scenario, form data are restricted to ASCII codes. -> If the method is “post” -, the user agent conducts an HTTP post transaction using the value of the action attribute and a message created according to the content type specified by the enctype attribute
This method is best when encode a string to used in a query part of a url. it returns a string in which all non-alphanumeric characters except -_. have replece with a percentege(%) sign . the urldecode->Decodes url to encode string as any %and other symbole are decode by the use of the urldecode() function
PEAR is a framework and distribution system for reusable PHP components.The project seeks to provide a structured library of code, maintain a system for distributing code and for managing code packages, and promote a standard coding style.PEAR is broken into three classes: PEAR Core Components, PEAR Packages, and PECL Packages. The Core Components include the base classes of PEAR and PEAR_Error, along with database, HTTP, logging, and e-mailing functions. The PEAR Packages include functionality providing for authentication, networking, and file system features, as well as toolsfor working with XML and HTML templates
Exception Handling is used to handle the error. It can handle all types oferror like Warning, Notice, User defined Error message etc but unfortunately it can not handle fatal error.read more..
Full form ofORMis ObjectRelationMapper. ORM is programming technique for converting data between incompatible type systems in object-oriented programming languages. Data management tasks in object-oriented programming(OOP) are typically implemented by manipulating objects that are almost always non-scalar values.For example, consider an address book entry that represents a single person along with zero or more phone numbers and zero or more addresses. This could be modeled in an object-oriented implementation by a "Person object" with attributes/fields to hold each data item that the entry comprises: the person's name,a list of phone numbers, and a list of addresses. The list of phone numbers would itself contain "PhoneNumber objects" and so on. The address book entry is treatedas a single object by the programming language (it can be referenced by a single variable containing a pointer to the object, for instance)
Restart Apache web server over the SSH/etc/init.d/apache2 restart Stop Apache web server over the SSH/etc/init.d/apache2 stop Start Apache web server over the SSH/etc/init.d/apache2 start httpd Server restart commandservice httpd restart httpd Server Stop command service httpd stop httpd Server Stop commandservice httpd start
Persistent connections are links that do not close when the execution of your script ends. When a persistent connection is requested, PHP checks if there's already an identical persistent connection (that remained open from earlier) - and if it exists, it uses it. If it does not exist, it creates the link. Persistent connections are good if the overhead to create a link to your SQL serveris high. Whether or not this overhead is really high depends on many factors. Like, what kind of database it is, whether or not it sits on the same computer on which your web server sits, how loaded the machine the SQL server sits on is and so forth. The bottom line is that if that connection overhead is high, persistent connections help you considerably
1. A data member belongs to an object of a class whereas local variable belongs to its current scope. 2. A local variable is declared within the body of a function and can be used only from the point at which it is declared to the immediately following closing brace. 1. A data member belongs to an object of a class whereas local variable belongs to its current scope. 2. A local variable is declared within the body of a function and can be used only from the point at which it is declared to the immediately following closing brace. 3. Data members are accessible to all member function of the class. Local variableare not accessible in any another function or class. 2. The only rule is that static methods or properties are out of object context. 3. Public function of class can be access by scope resolution operator (i.e ::) and Object Reference Operator (i.e ->) but public data member can't be access through scope resolution operator
move_uploaded_file( string filename, string destination)
CRYPT(), MD5()
The strip_tags() function enables us to clean a string from the HTML tags
The function get_magic_quotes_gpc() tells us whether the magic quotesis switched on or no
We have to enable the Magic quotes entry in the configuration file of PHP.
The strips lashes function enables us to remove the escape characters before apostrophes in a string
addslashes function enables us to escape data before storage into the database
The unset() function is dedicated for variable management. It will make a variable undefined
The unlink() function is dedicated for file system handling. It simply deletes the file given as entry
If we want to check whether a variable has a value or not, it is possible to use the empty() function
It is possible to use the dedicated function, ctype_alnum to check whether it is an alphanumeric value or not
It is possible to use the dedicated function, is_numeric() to check whether it is a number or not
To access the data sent this way, you use the $_POST array.Imagine you have a form field called 'var’ on the form, when the user clicks submit to the post form, you can then access the value like this: $_POST[“var”];
In order to access the data sent via the GET method, we you use $_GET array like this: www.url.com?var=value$variable = $_GET[“var”]; this will now contain 'value’
file_get_contents() lets reading a file and storing it in a string variable.
The most common and used way is to get data into a format supported by Excel. For example, it is possible to write a .csv file, to choose for example comma as separator between fields and then to open the file with Excel.
This is a PHP syntax error expressing that a mistake at the line x stops parsing and executing the program
The set_time_limit(0) added at the beginning of a script sets to infinite the time of execution to not have the PHP error 'maximum execution time exceeded’.It is also possible to specify this in the php.ini file
To be able to display a human-readable result we use print_r()
.htaccess files are configuration files of Apache Server which providea way to make configuration changes on a per-directory basis. A file,containing one or more configuration directives, is placed in a particulardocument directory, and the directives apply to that directory, and allsubdirectories thereof
The header() function sends a raw HTTP header to a client.We can use herder() function for redirection of pages. It is important to notice that header() mustbe called before any actual output is seen
Yes variable name casesensitive and we can’t start a variable with number like $4name as A valid variable name starts with a letter or underscore, followed by any number of letters, numbers, or underscores
Rasmus Lerdorf is known as the father of PHP that started developmentof PHP in 1994 for their own Personal Home Page (PHP) and they released PHP/FI (Forms Interpreter) version 1.0 publicly on 8 June 1995 But in 1997 two Israeli developers named Zeev Suraski and Andi Gutmans rewrote the parser that formedthe base of PHP 3 and then changed the language’s name to the PHP: Hypertext Preprocessor.
Yes variable name casesensitive and we can’t start a variable with number like $4name as A valid variable name starts with a letter or underscore, followed by any number of letters, numbers, or underscores
exit() function which stops the current php script (Execution of the page).
Here, if the value is non-zero, then if($var==’value’) is true and it will execute. If you put the value on the left, then it throws the PHP parse time error
URLencode returns a string in which all non-alphanumeric characters except -_. have been replaced with a percent (%) sign followed by two hex digits and spaces encoded as plus (+) signs. It is encoded the same way that the posted data from a WWW formis encoded, that is the same way as in application/x-www-form-urlencoded media type. urldecode decodes any %## encoding in the given string
The functions are getimagesize() for size, imagesx() for width and imagesy() for height.
imagetypes() gives the image format and types supported by the currentversion of GD-PHP.
GD library is needed to be able execute image functions
We use the operator '==’ to test is two object are instanced from the same class and have same attributes and equal values. We can test if two object are refering to the same instance of the same class by the use of the identity operator '===’.
If we would like to pass values througn a form or an URL then we need to encode and to decode them using htmlspecialchars() and urlencode()
'final’ is introduced in PHP5. Final class means that this class cannot beextended and a final method cannot be overrided
PHP includes only single inheritance, it means that a class can be extended from only one single class using the keyword 'extended’
To be able to display the output directly to the browser, we have to use the special tag
Abstract class: abstract classes are the class where one or moremethods are abstract but not necessarily all method has to be abstract. Abstract methods are the methods, which are declare in its class but not defined. The definition of those methods must be in its extending class. Interface: Interfaces are one type of class where all the methods are abstract. That means all the methods only declared but not defined. All the methods must be defined by its implemented class.
PHP - Hypertext PreProcessor, Earlier known as Personal Homape Page PHP is an Open-source server side scripting language that is embedded in to HTML and used for web development
PHP Syntax - A PHP script start with
Features of PHP - Simple Highly Flexible Platform Independent Interpreted Fast Open source Secure Large PHP Community
GET and POST are used to send information from client browser to web server. In case of GET the information is send via GET method in name/value pair and is URL encoded. The default GET has a limit of 512 characters. The POST method transfers the information via HTTP Headers. The POST method does not have any restriction in data size to be sent. POST is used for sending data securely and ASCII and binary type’s data. The $_REQUESTcontains the content of both $_GET, $_POST and $_COOKIE
PEAR means “PHP Extension and Application Repository”. it extends PHP and provides a higher level of programming for web developers
PHP means PHP: Hypertext Preprocessor
Yes. We can use the get_browser() function to get the details of the browser auser is using. This information is usually found inside the browscap.ini file
CAPTCHAis the short form of Completely Automated Public Turing Test. It?s a step taken to ensure that a feature is not abused in a way it?s not meant to beused. We use CAPTCHAS for general form submissions, registrations, user generated content and so on to prevent spam bots from clogging up the system or spamming
1. Static methods are that can be accessed by using the scope resolution operator (i.e ::) and object reference operator ( i.e.-> ). For example HelloClass::mystatic(); $helloClass->mystatic(); class MyClass{ static function mystatic() { echo "this was declared static!\n"; } } $obj = new MyClass(); MyClass::mystatic(); $obj->mystatic();
Single inheritance. Multiple Level inheritance
Email functionality isinbuilt with PHP. PHP providemail() with use of this, we can sen an email to user or subscriber. We can sendhtml/textemail. We can sendattachmentwith email. We can also use option likecc, bc and bcc. We can also set the values inheader. We can also use third party API like (gmail, yahoo etc) to send email
$date1 = date(“Y-m-d”); $date2 = “2006-08-15??; $days = (strtotime($date1) - strtotime($date2)) / (60 * 60 * 24);
The generic syntax for grant is as following > GRANT [rights] on [database/s] TO [username@hostname] IDENTIFIED BY [password] now rights can be a) All privileges b) combination of create, drop, select, insert, update and delete etc.We can grant rights on all databse by using *.* or some specific database by database.* or a specific table by database.table_name username@hotsname can be either username@localhost, username@hostname and username@% where hostname is any valid hostname and % represents any name, the *.* any condition password is simply the password of userThe generic syntax for revoke is as following> REVOKE [rights] on [database/s] FROM [username@hostname] now rights can be as explained above a) All privileges b) combination of create, drop, select, insert, update and delete etc. username@hotsname can be either username@localhost, username@hostname and username@% where hostname is any valid hostname and % represents any name, the *.* any condition
1. Never include, require, or otherwise open a file with a filename based on user input, without thoroughly checking it first. 2. Be careful with eval() Placing user-inputted values into the eval() function can be extremely dangerous. You essentially give the malicious user the ability to execute any command he or she wishes! 3. Be careful when using register_globals = ON It was originally designed to make programming in PHP easier (and that it did), but misuse of it often led to security holes 4. Never run unescaped queries 5. For protected areas, use sessions or validate the login every time. 6. If you don ™t want the file contents to be seen, give the file a .php extension
The generic syntax for grant is as following : > GRANT [rights] on [database/s] TO [username@hostname] IDENTIFIED BY[password]now rights can be a) All privileges b) combination of create, drop, select, insert, update and delete etc. We can grant rights on all databse by using *.* or some specificdatabase by database.* or a specific table by database.table_name username@hotsname can be either username@localhost, username@hostname and username@% where hostname is any valid hostname and % represents any name, the *.*any condition password is simply the password of user. The generic syntax for revoke is as following : > REVOKE [rights] on [database/s] FROM [username@hostname] now rights can be as explained above a) All privileges b) combination of create, drop, select, insert, update and delete etc.username@hotsname can be either username@localhost, username@hostname and username@% where hostname is any valid hostname and % represents any name, the *.*any condition
PHP and Javascript cannot directly interacts since PHP is a server side language and Javascript is a client side language. However we can exchange PHP INTERVIEW QUESTIONS 17variables since PHP is able to generate Javascript code to be executed by the browser and it is possible to pass specific variables back to PHP via the URL
eregi_replace() function is identical to ereg_replace() except that this ignores case distinction when matching alphabetic characters.eregi_replace() function is identical to ereg_replace() except that this ignores case distinction when matching alphabetic characters
by changing the following setup at php.inimax_execution_time = 30; Maximum execution time of each script, in seconds
By default the maximum size is 2MB. and we can change the following setup at php.iniupload_max_filesize = 2M
To know the Image type use exif_imagetype () function To know the Image size use getimagesize () function To know the image width use imagesx () function To know the image height use imagesy() function
This is not actually a real function, It is a language construct. So you can use with out parentheses with its argument list. Example print('PHP Interview questions'); print 'Job Interview ');
PEAR is known as PHP Extension and Application Repository. It provides structured library to the PHP users and also gives provision for package maintenance
PEAR(PHP Extension and Application Repository) is a framework and repository for reusable PHP components. PEAR is a code repository containing allkinds of php code snippets and libraries. PEAR also offers a command-line interface that can be used to automatically install "packages". $message vs. $$message in PHP. $message is a variable with a fixed name. $$message is a variable whose name is stored in $message. If $message contains "var", $$message is the same as $var.Echo vs. print statement. PHP INTERVIEW QUESTIONS 4echo() and print() are language constructs in PHP, both are used to output strings. The speed of both statements is almost the same. echo() can take multiple expressions whereas print cannot take multiple expressions. Print return true or false based on success or failure whereas echo doesn't return true or false
No. There is no way to send emails directly using JavaScript.But you can use JavaScript to execute a client side email program send the email using the “mailto” code. Here is an example: function myfunction(form) { tdata=document.myform.tbox1.value; location=”mailto:[email protected]?subject=...”; return true; }
LAMP is an open-source solution stack that contains everything you need to create a complete, stand-alone platform for your web application—Linux, Apache, MySQL, and PHP. This question is a good opportunity for your prospective programmer to detail any experience they have taking a web project from conception to completion.
This is a good way to gauge a developer’s understanding of autoloading. Whenever a class is instantiated, a function is triggered. You can register a function with the spl_autoload que detailed below, courtesy of php.net:
bool spl_autoload_register ([ callable $autoload_function [, bool$throw = true [, bool $prepend = false ]]] )
Design patterns are essentially best-practice templates that programmers can use to consistently write well-designed code more quickly. Here are a couple examples along with their use cases:
The Singleton: Used when you only want to allow access to one instance of a particular class. The Factory: The factory pattern makes it easier to create multiple classes without repeating code. To change, rename, or replace the class, simply modify the factory.
$pear = 'PEAR ’;
$pear[12] = 'PHP Extension and Application Repository’;
This question reveals a few interesting things about the way PHP interprets code. The value of $pear in the code above will be the string "PEAR P" or the string "PEAR " followed by seven spaces, followed by "P," which is the first character in the string "PHP Extension and Application Repository." The value returned by strlen($pear) will thus be 13. Since an element of a string can only consist of one character, and the count of elements within a string starts with 0, $pear[12] sets the 13th character of the string to the letter "P." Interestingly enough, we chose to set the 13th value of a string that only has five characters. While other language interpreters might have thrown an out-of-bounds index error, PHP is more forgiving and fills in the blanks with empty spaces.
var_dump(42 == 042);
var_dump('042’ == 42);
var_dump('042’ === 42);
This question quizzes the coder on how the PHP interpreter handles numbers and strings. i. var_dump(42 == 042); will output bool(false) because the PHP interpreter treats leading zeroes as octals. 042 is 32 in decimal, which does not equal 42. ii. var_dump('042’ == 42); will output bool(true) because PHP interpreter will coerce the string into an integer but ignore the leading zero. 42 is equal to 42. iii. var_dump('042’ === 42); will output bool(false) because the === operator performs a stricter comparison and will not coerce the integer into a string.
$x = true or false;
var_dump($x);
$x = true and false;
var_dump($x);
This question is designed to test a coder’s knowledge of the order of operations. The first block of code is more straightforward, evaluating to true because of the "or" operator. The second code block, however, would typically be expected to evaluate to false. Instead, it evaluates to true because of how the PHP interpreter handles the order of operations: "=" is prioritized leading to the following equivalent code snippet: $x = true; // sets $x equal to true True and false; // evaluates to false, but does not affect anything
$x = 2
$y = 4
$z = 6
if($z > $y > $x) {
echo "true";
}else{
echo "false";
}
At first glance, one would expect the boolean to evaluate to "true" because 6 > 4 > 2. However, the correct answer is "false" because PHP will first evaluate $z > $y, which returns a boolean value of 1 or true. It is this boolean value of 1 that is compared to the next integer in the chain, bool(1) > $z, which will result in NULL and echo "false."
mysql -u username -p databasename tablename < sqlfilename> (It will prompt for password)
1) Login to Putty/Console 2) Execute following commands to export the sql dump into server. mysqldump -u username -p databasename tablename > sqlfilename.sql (It will prompt password)
1) Login to Putty/Console 2) Go to the directory where your file exist (suppose file name is file.zip) 3) Use the following command to copy the file frome current server to another server scp file.zip username@hostname:/foldername (It will prompt password) (username, hostname is another server)
1) Make a zip of sql dump file and upload the zip file to server through FTP. 2) Login to Putty/Console 3) Go the directory with use of cd command, the location where you have upload thezip file. 4) unizip that zip file, with following command unzip zipfilename.zip 3)Import the sql dump file with use of following command. mysql -u username -p databasename < sqlfilename> (It will for prompt password)
SELECT DATEDIFF(“2007-03-07′′,”2005-01-01′′);
SELECT CURDATE(); CURRENT_DATE() = CURDATE() for time use SELECT CURTIME(); CURRENT_TIME() = CURTIME()
$result = mysql_query($sql, $db_link); $num_rows = mysql_num_rows($result); echo “$num_rows rows found”;
Use this for mysql >SELECT COUNT(*) FROM table_name;
If the operating system or filesystem places a limit on the number of files in a directory, MySQL is bound by that constraint. The efficiency of the operating systemin handling large numbers of files in a directory can place a practical limit on the number of tables in a database. If the time required to open a file in the directory increases significantly as the number of files increases, database performance can be adversely affected. The amount of available disk space limits the number of tables. MySQL 3.22 had a 4GB (4 gigabyte) limit on table size. With the MyISAM storage engine in MySQL 3.23, the maximum table size was increased to 65536 terabytes (2567 1 bytes). With this larger allowed table size, the maximum effective table sizefor MySQL databases is usually determined by operating system constraints on file sizes, not by MySQL internal limits.The InnoDB storage engine maintains InnoDB tables within a tablespace that can be created from several files. This allows a table to exceed the maximum individual file size. The tablespace can include raw disk partitions, which allows extremely large tables. The maximum tablespace size is 64TB. The following table lists some examples of operating system file-size limits. This is only a rough guide and is not intended to be definitive.For the most up-to-date information, be sure to check the documentation specific to your operating system.Operating System File-size LimitLinux 2.2-Intel 32-bit 2GB (LFS: 4GB)Linux 2.4+ (using ext3 filesystem) 4TB Solaris 9/10 16TB NetWare w/NSS filesystem 8TB Win32 w/ FAT/FAT32 2GB/4GB Win32 w/ NTFS 2TB (possibly larger) MacOS X w/ HFS+ 2TB
describe Table-Name;
MySQL set can take zero or more values but at the maximum it can take 64 values
The following table describes the maximum length for each type of identifier.Identifier Maximum Length (bytes) Database64 Table 64 Column 64 Index 64 Alias 255 There are some restrictions on the characters that may appear in identifiers
The syntex for repairing a MySQL table isREPAIR TABLENAME, [TABLENAME, ], [Quick],[Extended]This command will repair the table specified if the quick is given the MySQL will doa repair of only the index tree if the extended is given it will create index row by row
we can always fetch from one database and rewrite to another. here is a nice solutionof it.
$db1 = mysql_connect(“host”,”user”,”pwd”) mysql_select_db(“db1??, $db1); $res1 = mysql_query(“query”,$db1);$db2 = mysql_connect(“host”,”user”,”pwd”) mysql_select_db(“db2??, $db2); $res2 = mysql_query(“query”,$db2);At this point you can only fetch records from you previous ResultSet, i.e $res1 “ But you cannot execute new query in $db1, even if you supply the link as because the link was overwritten by the new db. so at this point the following script will fail $res3 = mysql_query(“query”,$db1); //this will failSo how to solve that? take a look below. $db1 = mysql_connect(“host”,”user”,”pwd”) mysql_select_db(“db1??, $db1); $res1 = mysql_query(“query”,$db1); $db2 = mysql_connect(“host”,”user”,”pwd”, true) mysql_select_db(“db2??, $db2); $res2 = mysql_query(“query”,$db2); So mysql_connect has another optional boolean parameter which indicates whether alink will be created or not. as we connect to the $db2 with this optional parameter setto 'true’, so both link will remain live. now the following query will execute successfully. $res3 = mysql_query(“query”,$db1);
• first of all instead of using select * from table1, use select column1, column2, column3.. from table1 • Look for the opportunity to introduce index in the table you are querying. • use limit keyword if you are looking for any specific number of rows from the result set.
MySQL fetch object will collect first single matching record where mysql_fetch_array will collect all matching records from the table in an array
The syntex for repairing a mysql table is: REPAIR TABLE tablename REPAIR TABLE tablename QUICK REPAIR TABLE tablename EXTENDED This command will repair the table specified. If QUICK is given, MySQL will do a repair of only the index tree. If EXTENDED is given, it will create index row by row.
The mysqli extension, or as it is sometimes known, the MySQL improved extension, was developed to take advantage of new features found in MySQL systems versions4.1.3 and newer. The mysqli extension is included with PHP versions 5 and later.The mysqli extension has a number of benefits, the key enhancements over the mysql extension being: =>Object-oriented interface =>Support for Prepared Statements =>Support for Multiple Statements =>Support for Transactions =>Enhanced debugging capabilities =>Embedded server support
The PDO ( PHP Data Objects ) extension defines a lightweight, consistent interface for accessing databases in PHP.
if you are using the PDO API, you could switch the database server you used, from say PgSQL to MySQL,
and only need to make minorchanges to your PHP code.
While PDO has its advantages, such as a clean, simple, portable API but its maindisadvantage is that it doesn’t allow
you to use all of the advanced features that are available in the latest versions of MySQL server.
For example, PDO does not allow you to use MySQL’s support for Multiple Statements.
Just need to use below code for connect mysql using PDO
try {
$dbh = new PDO(“mysql:host=$hostname;dbname=databasename”, $username, $password);
$sql = “SELECT * FROM employee”;
foreach ($dbh->query($sql) as $row)
{ print $row['employee_name'] .’ - '. $row['employee_age'] ; }}
catch(PDOException $e){
echo $e->getMessage();
}
$host = "localhost"; $username = "root"; $password = ""; $conn = new PDO("mysql:host=$host;dbname=myDB", $username, $password); // set the PDO error mode to exception $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); echo "Connected successfully";
$host = "localhost"; $username = "root"; $password = "";$conn = mysqli_connect($host, $username, $password); //connect to server if ($conn->connect_error) { die("Connection failed: " . $conn->connect_error); } echo "Connected successfully";
$host = "localhost";
$username = "root";
$password = "";$conn = new mysqli($host, $username, $password);
//connect to server
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
echo "Connected successfully";
When we have to fetch records from more than one table we can use JOIN keyword. The process is known as joining the tables. There are various types of join like INNER JOIN, LEFT JOIN, RIGHT JOIN, and OUTER JOIN
Group By is used for retrieving information about a group of data. It is generally used with some aggregate function like SUM, AVG etc. ORDER BY is used to sort the records using column name. It can sort column in both ascending and descending order.
SQL or Structured Query Language is a programming language designed for managing data held in a Relational Database Management System. Mysql is a open source, relational database management System
Use this for mysql>SELECT COUNT(*) FROM table_name;
mysql_fetch_assoc function Fetch a result row as an associative array, While mysql_fetch_array() fetches an associative array, a numeric array, or both
The trim() function removes whitespaces or other predefined characters from bothsides of a string
oMysql_fetch_array Fetch a result row as an associative array, a numeric array, or both. omysql_fetch_object ( resource result ) Returns an object with properties that correspond to the fetched row and moves the internal data pointer ahead. Returns an object with properties that correspond to the fetched row, or FALSE if there areno more rows omysql_fetch_row() fetches one row of data from the result associated with the specified result identifier. The row is returned as an array. Each result column is stored in an array offset, starting at offset 0
It is used to escapes special characters in a string for use in an SQL statement
There is a good page in the php manual on the subject, in short mysql_pconnect() makes a persistent connection to the database which means a SQL link that do not close when the execution of your script ends. mysql_connect()provides only for the databasenewconnection while using mysql_pconnect , the function would first try to find a (persistent) link that's already open with the same host, username and password. If one is found, an identifier for it will be returned instead of opening a new connection... the connection to the SQL server will not be closed when the execution of the script ends. Instead, the link will remain open for future use
We can create MySQL Database with the use of mysql_create_db(“Database Name”)
mysql_fetch_object() is similar to mysql_fetch_array(), with one difference - an object is returned, instead of an array. Indirectly, that means that you can only access the data by the field names, and not by their offsets (numbers are illegal property names)
AES_ENCRYPT () and AES_DECRYPT ()
Following are the advantage / disadvantage of SP. Advantage You do not need to deploy to make a change. Faster Easier to expand a system Disadvantages Refactoring is harder. Renaming or changing where the store proc is might produce a bad effect. Unit testing stored proc require code assistance outside the DB
The mysql_error() message will tell us what was wrong with our mysqlquery
The mysql_fetch_object() function collects the first single matching record where mysql_fetch_array() collects all matching records from the table in an array
mysql_affected_rows() return the number of entries affected by an SQLquery
The result set can be handled using mysql_fetch_array, mysql_fetch_assoc, mysql_fetch_object or mysql_fetch_row
mysql_pconnect() ensure a persistent connection to the database, it means that the connection do not close when the the PHP script ends
AES_ENCRYPT () and AES_DECRYPT ()
MySQL set can take zero or more values but at the maximum it can take 64 values.
The following table describes the maximum length for each type of identifier. There are some restrictions on the characters that may appear in identifiers.
The syntex for repairing a MySQL table is REPAIR TABLENAME, [TABLENAME, ], [Quick],[Extended].This command will repair the table specified if the quick is given the MySQL will do a repair of only the index tree if the extended is givenit will create index row by row.
If you want to create a table, you can run the CREATE TABLE statement as shown in the following sample script: Remember that mysql_query() returns TRUE/FALSE on CREATE statements. If you run this script, you will get something like this:Table Tech_links created
The mysql_error() message will tell us what was wrong with our query, similar to the message we would receive at the MySQL console.
To backup: BACKUP TABLE tbl_name[,tbl_name ¦] TO '/path/to/backup/directory’ RESTORE TABLE tbl_name[,tbl_name ¦] FROM '/path/to/backup/directory’mysqldump: Dumping Table Structure and DataUtility to dump a database or a collection of database for backup or for transferring the data to another SQL server (not necessarily a MySQL server). The dump will contain SQL statements to create the table and/or populate the table. -t, no-create-info Don’t write table creation information (the CREATE TABLE statement). -d, “no-data Don’t write any row information for the table. This is very useful if you just want to get a dump of the structure for a table!
| encryption | decryption |
| AES_ENCRYT() | AES_DECRYPT() |
| ENCODE() | DECODE() |
| DES_ENCRYPT() | DES_DECRYPT() |
| ENCRYPT() | Not available |
| MD5() | Not available |
| OLD_PASSWORD() | Not available |
| PASSWORD() | Not available |
| SHA() or SHA1() | Not available |
| Not available | UNCOMPRESSED_LENGTH() |
We use DISTINCT keyword
Suppose take an example where you need to fetch all customer data where name stats with sa SELECT * FROM Customers WHERE name LIKE 'sa%'; Another case is where you need to fetch all customer data where kumar is found irrespective of the position (middle name or last name). SELECT * FROM Customers WHERE name LIKE '%kumar%';
Sum function works on the column basis and will return the sum of that particular row only
Both of them are open source software (so free of cost), supportcross platform. php is faster then ASP and JSP
SELECT CURDATE(); CURRENT_DATE() = CURDATE() for time use SELECT CURTIME(); CURRENT_TIME() = CURTIME()
$result = mysql_query($sql, $db_link); $num_rows = mysql_num_rows($result); echo “$num_rows rows found”;
Following tables (Storage Engine) we can create 1. MyISAM(The default storage engine IN MYSQL Each MyISAM table is stored on disk in three files. The files have names that begin with the table name and have an extension to indicate the file type. An .frm file stores the table format.The data file has an .MYD (MYData) extension. The index file has an .MYI (MYIndex) extension. ) 2. InnoDB(InnoDB is a transaction-safe (ACID compliant) storage engine for MySQL that has commit, rollback, and crash-recovery capabilities to protect user data.) 3. Merge 4. Heap (MEMORY)(The MEMORY storage engine creates tables with contents that are stored in memory. Formerly, these were known as HEAP tables. MEMORY is the preferred term, although HEAP remains supported for backward compatibility. ) 5. BDB (BerkeleyDB)(Sleepycat Software has provided MySQL with the Berkeley DB transactional storage engine. This storage engine typically is called BDB for short. BDB tables may have a greater chance of surviving crashes and are also capable of COMMIT and ROLLBACK operations on transactions) 6. EXAMPLE 7. FEDERATED (It is a storage engine that accesses data in tables of remote databases rather than in local tables. ) 8. ARCHIVE (The ARCHIVE storage engine is used for storing large amounts of data without indexes in a very small footprint. ) 9. CSV (The CSV storage engine stores data in text files using comma-separated values format.) 10. BLACKHOLE (The BLACKHOLE storage engine acts as a “black hole” that accepts data but throws it away and does not store it. Retrievals always return an empty result)
WeWe can always fetch from one database and rewrite to another. Here is a nice solution of it. $db1 = mysql_connect(”host”,”user”,”pwd”); mysql_select_db(”db1?, $db1); $res1 = mysql_query(”query”,$db1); $db2 = mysql_connect(”host”,”user”,”pwd”); mysql_select_db(”db2?, $db2); $res2 = mysql_query(”query”,$db2); At this point you can only fetch records from you previous ResultSet, i.e $res1 - But you cannot execute new query in $db1, even if yousupply the link as because the link was overwritten by the new db.so at this point the following script will fail $res3 = mysql_query(”query”,$db1); //this will failSo how to solve that? take a look below. $db1 = mysql_connect(”host”,”user”,”pwd”); mysql_select_db(”db1?, $db1); $res1 = mysql_query(”query”,$db1); $db2 = mysql_connect(”host”,”user”,”pwd”, true); mysql_select_db(”db2?, $db2);$res2 = mysql_query(”query”,$db2); So mysql_connect has another optional boolean parameter whichindicates whether a link will be created or not. As we connect to the $db2 with this optionalparameter set to 'true’, so both link willremain live. Now the following query willexecute successfully. $res3 = mysql_query(”query”,$db1);
Case Studio Smart Draw
First of all instead of using select * from table1, use select column1, column2, column3.. from table1 •Look for the opportunity to introduce index in the table you are querying. •use limit keyword if you are looking for any specific number of rows from the result set
To backup: BACKUP TABLE tbl_name[,tbl_name...] TO '/path/to/backup/directory’ RESTORE TABLE tbl_name[,tbl_name...] FROM '/path/to/backup/directory’mysqldump: Dumping Table Structure and DataUtility to dump a database or a collection of database for backup or for transferring the data to another SQL server (not necessarily a MySQL server). The dump will contain SQL statements to create the table and/or populate the table. -t, -no-create-info Don’t write table creation information (the CREATE TABLE statement). -d, -no-data Don’t write any row information for the table. This is very useful if you just want to get a dump of the structure for a table.
AES_ENCRYPT () and AES_DECRYPT ()
In MySql, the default table type is MyISAM. Each MyISAM table is stored on disk in three files. The files have names that begin with the table name and have an extension to indicate the file type. The '.frm’ file stores the table definition. The data file has a '.MYD’ (MYData) extension. The index file has a '.MYI’ (MYIndex) extension
SELECT DATEDIFF(’2007-03-07?,’2005-01-01?);
A stored procedure is a set of SQL commands that can be compiled and stored in the server. Once this has been done, clients don’t need to keep re-issuing the entire querybut can refer to the stored procedure. This provides better overall performance because the query has to be parsed onlyonce, and less information needs to be sent between the server and the client. You can also raise the conceptual level by having libraries of functions in the server. However, stored procedures of course do increase the load on the database server system, as more of the work is done on the server side and less on the client (application) side.Triggers will also be implemented. A trigger is effectively a type of stored procedure, one thatis invoked when a particular event occurs. For example, you can install a stored procedure that is triggered each time a record isdeleted from a transaction table and that stored procedure automatically deletes the corresponding customer from a customer table when all his transactions are deleted.Indexes are used to find rows with specific column values quickly.Without an index, MySQL must begin with the first row and then read through the entire table to find the relevant rows. The larger the table, the more this costs. If the table has an index for the columns in question, MySQL can quickly determine the position to seek to in the middle of the data file without having to look at all the data.If a table has 1,000 rows, this is at least 100 times faster than reading sequentially. Ifyou need to access most of the rows, it is faster to read sequentially, because this minimizes disk seeks
The function mysql_num_rows() returns the number of rows in a resultset.
you can use LOAD DATA INFILE file_name; syntax to load data from a text file. but you have to make sure that a) data is delimited b) columns and data matched correctly
ORDER BY [col1],[col2], ¦,[coln]; Tels DBMS according to what columns it should sort the result. If two rows will hawe the same value in col1 it will try to sort them according to col2 and so on. GROUP BY [col1],[col2], ¦,[coln]; Tels DBMS to group results with same value of column col1. You can use COUNT(col1), SUM(col1), AVG(col1) with it,if you want to count all items in group, sum all values or view average
Primary Key: A column in a table whose values uniquely identify the rows in the table. A primary key value cannot be NULL. Unique Key: Unique Keys are used to uniquely identify each row in the table. Therecan be one and only one row for each unique key value. So NULL can be a unique key.There can be only one primary key for a table but there can be more than one unique for a table
The normalization process involves getting our data to conform to three progressive normal forms, and a higher level of normalization cannot be achieved until the previous levels have been achieved (there are actually five normal forms, but the lasttwo are mainly academic and will not be discussed).First Normal FormThe First Normal Form (or 1NF) involves removal of redundant data from horizontal rows. We want to ensure that there is no duplication of data in a given row, and that every column stores the least amount of information possible (making the field atomic).Second Normal FormWhere the First Normal Form deals with redundancy of data across a horizontal row, Second Normal Form (or 2NF) deals with redundancy of data in vertical columns. As stated earlier, the normal forms are progressive, so to achieve Second Normal Form, your tables must already be in First Normal Form.Third Normal FormI have a confession to make; I do not often use Third Normal Form. In Third NormalForm we are looking for data in our tables that is not fully dependant on the primary key, but dependant on another value in the table
DROP table customers; It will drop the table customers
Take an example DELETE FROM customer WHERE cid=150; In this case it will delete the record of the customer with customer id 150
INNER Join compares two tables and only returns results where a match exists. Records from the 1st table are duplicated when they match multiple results in the 2nd. INNER joins tend to make result sets smaller, but because records can be duplicated this isn’t guaranteed. LEFT join means keep all records from the 1st table no matter what and insert NULL values when the 2nd table doesn’t match. RIGHT Join means the opposite: keep all records from the 2nd table no matter what and insert NULL values when the 1st table doesn’t match
Primary Key: A column in a table whose values uniquely identify therows in the table. A primary key value cannot be NULL. Unique Key: Unique Keys are used to uniquely identify each row in thetable. There can be one and only one row for each unique key value. So NULL can be a unique key.There can be only one primary key for a table but there can be morethan one unique for a table
The SQL Server Driver for PHP v1.0 is designed to enable reliable, scalable integration with SQL Server for PHP applications deployed on the Windows platform. The Driver for PHP is a PHP 5 extension that allows the reading and writing of SQL Server data from within PHP scripts. using MSSQL or ODBC modules we can access Microsoft SQL server.
Cross-site scripting (XSS) is a type of computer security vulnerability typically found in web applications which allow code injection by malicious web users into the web pages viewed by other users. Examples of such code include HTML code and client-side scripts. SQL injection is a code injection technique that exploits a security vulnerability occurring in the database layer of an application. The vulnerability is present when user input is either incorrectly filtered for string literal escape characters embedded in SQL statements or user input is not strongly typed and thereby unexpectedly executed
ORDER BY [col1],[col2],...,[coln]; Tells DBMS according to what columns it should sort the result. If two rows will have the same value in col1it will try to sort them according to col2 and so on.GROUP BY[col1],[col2],...,[coln]; Tells DBMS to group results with same value of column col1. You can use COUNT(col1), SUM(col1), AVG(col1) with it, if you want to count all items in group, sum all values or view average.