MYSQL_REAL_ESCAPE_STRING(3)						 1					       MYSQL_REAL_ESCAPE_STRING(3)

mysql_real_escape_string - Escapes special characters in a string for use in an SQL statement

SYNOPSIS

       Warning

	      This  extension  is deprecated as of PHP 5.5.0, and will be removed in the future. Instead, the MySQLi or PDO_MySQL extension should
	      be used. See also MySQL: choosing an API guide and related FAQ for more information. Alternatives to this function include:

		     omysqli_real_escape_string(3)

		     o PDO::quote

       string mysql_real_escape_string (string	$unescaped_string, [resource  $link_identifier = NULL])

DESCRIPTION

	Escapes special characters in the $unescaped_string, taking into account the current character set of the connection so that it is safe to
       place it in a mysql_query(3). If binary data is to be inserted, this function must be used.

       mysql_real_escape_string(3)  calls  MySQL's  library function mysql_real_escape_string, which prepends backslashes to the following charac-
       ters: x00, 
, 
, , ', " and x1a.

	This function must always (with few exceptions) be used to make data safe before sending a query to MySQL.

       Caution

	      Security: the default character set

	       The character set must be set either at the server  level,  or  with  the  API  function  mysql_set_charset(3)  for  it	to  affect
	      mysql_real_escape_string(3). See the concepts section on character sets for more information.

	      o $unescaped_string
		- The string that is to be escaped.

	      o $
		link_identifier  -The  MySQL  connection.  If  the  link  identifier is not specified, the last link opened by mysql_connect(3) is
		assumed. If no such link is found, it will try to create one as if mysql_connect(3) was called with no arguments. If no connection
		is found or established, an E_WARNING level error is generated.

	Returns the escaped string, or FALSE on error.

       Example #1

	      Simple mysql_real_escape_string(3) example

	      <?php
	      // Connect
	      $link = mysql_connect('mysql_host', 'mysql_user', 'mysql_password')
		  OR die(mysql_error());

	      // Query
	      $query = sprintf("SELECT * FROM users WHERE user='%s' AND password='%s'",
			  mysql_real_escape_string($user),
			  mysql_real_escape_string($password));
	      ?>

       Example #2

	      An example SQL Injection Attack

	      <?php
	      // We didn't check $_POST['password'], it could be anything the user wanted! For example:
	      $_POST['username'] = 'aidan';
	      $_POST['password'] = "' OR ''='";

	      // Query database to check if there are any matching users
	      $query = "SELECT * FROM users WHERE user='{$_POST['username']}' AND password='{$_POST['password']}'";
	      mysql_query($query);

	      // This means the query sent to MySQL would be:
	      echo $query;
	      ?>

	       The query sent to MySQL:

	      SELECT * FROM users WHERE user='aidan' AND password='' OR ''=''

	       This would allow anyone to log in without a valid password.

       Note

	       A  MySQL  connection  is  required before using mysql_real_escape_string(3) otherwise an error of level E_WARNING is generated, and
	      FALSE is returned. If $link_identifier isn't defined, the last MySQL connection is used.

       Note

	       If magic_quotes_gpc is enabled, first apply stripslashes(3) to the data. Using this function on data which has already been escaped
	      will escape the data twice.

       Note

	       If this function is not used to escape data, the query is vulnerable to SQL Injection Attacks.

       Note

	      mysql_real_escape_string(3) does not escape % and _. These are wildcards in MySQL if combined with LIKE, GRANT, or REVOKE.

       mysql_set_charset(3),  mysql_client_encoding(3),  addslashes(3),  stripslashes(3), The magic_quotes_gpc directive, The magic_quotes_runtime
       directive.

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