mysql_result

mysql_query

[edit] Last updated: Fri, 25 Nov 2011

mysql_real_escape_string

(PHP 4 >= 4.3.0, PHP 5)

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

Description

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

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(). If binary data is to be inserted, this function must be used.

mysql_real_escape_string() calls MySQL's library function mysql_real_escape_string, which prepends backslashes to the following characters: \x00, \n, \r, \, ', " and \x1a.

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

Parameters

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

Return Values

Returns the escaped string, or FALSE on error.

Examples

Example #1 Simple mysql_real_escape_string() 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.

Notes

Note:
A MySQL connection is required before using mysql_real_escape_string() 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() 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() does not escape % and _. These are wildcards in MySQL if combined with LIKE, GRANT, or REVOKE.


<?php

/**

 * @author upadrian@gmail.com

 * Simplified version for array escape using mysql_real_escape_string

 * for db store. Key names are not escaped beacuse i don't plain to 

 * include in a sql. 

 * 

*/



function mres($q) {

    if(is_array($q)) 

        foreach($q as $k => $v) 

            $q[$k] = mres($v); //recursive

    elseif(is_string($q))

        $q = mysql_real_escape_string($q);

    return $q;

}



?>

dan at marginallyclever dot com 08-Mar-2011 09:43


// Simplify, and don't forget to check the key names.



function from_array($x=null) {

  if(!isset($x)) return null;

  else if(is_string($x)) return mysql_real_escape_string($x);

  else if(is_array($x)) {

    foreach($x as $k=>$v) {

      $k2=mysql_real_escape_string($k);

      if($k!=$k2) unset($x[$k]);

      $x[$k2]=from_array($v);

    }

    return $x;

  }

}



// call it with $x=from_array($_POST['key_name']);

// or even $_POST=from_array($_POST);

stefan dot van dot beusekom at gmail dot com 31-Jan-2011 01:36


Following is a recursive function that makes all the strings it finds safe for data entry. If the underlying value is an array, it will loop through that array as well, to inifity. So any array depth is allowed. This might come in handy when dealing with sessions, posts, gets or whatnot arrays, where you immediately want to make use of the data without having to filter the data first.



<?php

        /*

         * Created by: Stefan van Beusekom

         * Created on: 31-01-2011

         * Description: A method that ensures safe data entry, and accepts either strings or arrays. If the array is multidimensional, 

         *                     it will recursively loop through the array and make all points of data safe for entry.

         * parameters: string or array;

         * return: string or array;

         */

        public function filterParameters($array) {

        

            // Check if the parameter is an array

            if(is_array($array)) {

                // Loop through the initial dimension

                foreach($array as $key => $value) {

                    // Check if any nodes are arrays themselves

                    if(is_array($array[$key]))

                        // If they are, let the function call itself over that particular node

                        $array[$key] = $this->filterParameters($array[$key]);

                

                    // Check if the nodes are strings

                    if(is_string($array[$key]))

                        // If they are, perform the real escape function over the selected node

                        $array[$key] = mysql_real_escape_string($array[$key]);

                }            

            }

            // Check if the parameter is a string

            if(is_string($array))

                // If it is, perform a  mysql_real_escape_string on the parameter

                $array = mysql_real_escape_string($array);

            

            // Return the filtered result

            return $array;

        

        }



?>

feedr 05-Dec-2010 04:38


Just a little function which mimics the original mysql_real_escape_string but which doesn't need an active mysql connection. Could be implemented as a static function in a database class. Hope it helps someone.





<?php


function mysql_escape_mimic($inp) {


    if(is_array($inp))


        return array_map(__METHOD__, $inp);





    if(!empty($inp) && is_string($inp)) {


        return str_replace(array('\\', "\0", "\n", "\r", "'", '"', "\x1a"), array('\\\\', '\\0', '\\n', '\\r', "\\'", '\\"', '\\Z'), $inp);


    }





    return $inp;


}


?>

Anonymous 11-Nov-2010 05:44


calling this function twice, or on a string for which quotes have already been escaped, causes the quotes to be escaped twice.An example is where we have to check for magic_quotes_gpc  before calling mysql_escape_string to sanitize the inputs.





The following function can be used to escape singe and double quotes in a string with out the risk of escaping quotes twice.This function  escapes a quote, only if it hasn't already been escaped.





<?php


function safe_string_escape($str)


{


   $len=strlen($str);


    $escapeCount=0;


    $targetString='';


    for($offset=0;$offset<$len;$offset++) {


        switch($c=$str{$offset}) {


            case "'":


            // Escapes this quote only if its not preceded by an unescaped backslash


                    if($escapeCount % 2 == 0) $targetString.="\\";


                    $escapeCount=0;


                    $targetString.=$c;


                    break;


            case '"':


            // Escapes this quote only if its not preceded by an unescaped backslash


                    if($escapeCount % 2 == 0) $targetString.="\\";


                    $escapeCount=0;


                    $targetString.=$c;


                    break;


            case '\\':


                    $escapeCount++;


                    $targetString.=$c;


                    break;


            default:


                    $escapeCount=0;


                    $targetString.=$c;


        }


    }


    return $targetString;


}


echo safe_string_escape("asda'sda\'dsad\"sadasd'");


?>





above code echoes 





asda\'sda\'dsad\"sadasd\'





You can see that the second single quote wasnt escaped again..

m-t at live dot fr 17-Oct-2010 04:30


You should use mysql_real_escape_string only before inserting the data into your table, otherwise you could just use this function :



function reverse_escape($str)

{

  $search=array("\\\\","\\0","\\n","\\r","\Z","\'",'\"');

  $replace=array("\\","\0","\n","\r","\x1a","'",'"');

  return str_replace($search,$replace,$str);

}

anonymous at host dot com 16-Sep-2010 09:28


You can also use the escape function in a manner as shown in the snapshot out of my own browsertools class:





<?php


//


// MySQL Database connection


//


public function mysqlConnect($host, $user, $password, $database) {


    $this->mysql = mysql_connect($host, $user, $password);


    if (!$this->mysql) die(mysql_error());


    mysql_select_db($database, $this->mysql);


}





//


// MySQL Query


// usage:


//    $query such as "SELECT * FROM users WHERE nick = '%s' AND pass = '%s'"


//      where %s are the placeholders for the parameters


// call:


//    $__->mysqlQuery( $query, arg0, arg1, arg2, ... )


// description:


//    The parameters given to the function are escaped through mysql_real_escape_string(),


//    merged with the query and then given to the mysql_query function.


// returns:


//    Array of lines returned by the MySQL Database


//


public function mysqlQuery($query) {


    $numParams = func_num_args();


    $params = func_get_args();


    


    if ($numParams > 1) {


        for ($i = 1; $i < $numParams; $i++){


            $params[$i] = mysql_real_escape_string($params[$i]);


        }


        


        $query = call_user_func_array('sprintf', $params);


    }


    


    $this->result = mysql_query($query, $this->mysql);


    if (!$this->result) die(mysql_error());


    $ret = array();


    while ($row = mysql_fetch_assoc($this->result)) {


        $ret[] = $row;


    }


    mysql_free_result($this->result);


    return $ret;


}


?>

paralescuoctavian at gmail dot com 12-Sep-2010 12:28


Also don't forget to escape $_COOKIE array before quering the database. In firefox you can edit cookies and insert and inject harmful sql queries.





<?php


  foreach ($_COOKIE as $key => $value) {


    if(get_magic_quotes_gpc()) $_COOKIE[$key]=stripslashes($value);


    $_COOKIE[$key] = mysql_real_escape_string($value);


  }


?>

adelbenzarti at yahoo dot fr 19-Jun-2010 10:05


The function mysql_real_escape_string helps the developer to insert data without having troubles in the process or having risks of SQL Injection.

You can develop a similar function :

<?php

        function escape($str)

        {

                $search=array("\\","\0","\n","\r","\x1a","'",'"');

                $replace=array("\\\\","\\0","\\n","\\r","\Z","\'",'\"');

                return str_replace($search,$replace,$str);

        }

?>

manixrock -~- gmail ~-~ com 16-May-2010 11:07


I've come up with an easy way to more easily escape things in an sql query. The simpler things are, the lower the chance that you'll forget to escape something. I use a helper class:



<?php

class MysqlStringEscaper

{

    function __get($value)

    {

        return mysql_real_escape_string($value);

    }

}

$str = new MysqlStringEscaper;

?>



then whenever I run a query I can simply do:



<?php

mysql_query("SELECT * FROM users WHERE name LIKE '{$str->$name}' LIMIT 10");

?>



This way it's easy to see what the variable is escaped as (other instances like $int or $list could be implemented), it's inline and it only changes the variable when it's inserted into the query.

hikmet1023 at hotmail dot com 25-Mar-2010 09:29


about DATA LENGTH and mysql_real_escape_string



i have just experienced that this function does not harm the data length at all. It seems to use the escaped string during insertion but still insert the UNESCAPED string:



I have tried INSERTing 50 char long string ( containing characters to be escaped) into 50 char long datafield. I could SELECT the data without any loss and i didnt need to UNESCAPE it! So the data comes ready cooked, just serve it to where you need to...



AND BEFORE GOING MAD typing, saving, changing for long hours:



as documented above, do not forget to stripslashes(yourstring) if you have to.



And as documented at mysql manuals: do not use SET NAMES, use mysql_set_charset

gustavo639 at gmail dot com 25-Feb-2010 03:17


I use:





<?php


public static function escaparParametros(){


        $numParametros = func_num_args();


        $parametros = func_get_args();





        for ($i = 0; $i < $numParametros; $i++){


            $parametros[$i] = mysql_real_escape_string($parametros[$i]);


        }





        return $parametros;


    }


?>

root at aeze dot ru 24-Feb-2010 05:42


Here my simple but very effective function for safe mysql queries.





<?php


/**


* USAGE: mysql_safe( string $query [, array $params ] )


* $query - SQL query WITHOUT any user-entered parameters. Replace parameters with "?"


*     e.g. $query = "SELECT date from history WHERE login = ?"


* $params - array of parameters


*


* Example:


*    mysql_safe( "SELECT secret FROM db WHERE login = ?", array($login) );    # one parameter


*    mysql_safe( "SELECT secret FROM db WHERE login = ? AND password = ?", array($login, $password) );    # multiple parameters


* That will result safe query to MySQL with escaped $login and $password.


**/


function mysql_safe($query,$params=false) {


    if ($params) {


        foreach ($params as &$v) { $v = mysql_real_escape_string($v); }    # Escaping parameters


        # str_replace - replacing ? -> %s. %s is ugly in raw sql query


        # vsprintf - replacing all %s to parameters


        $sql_query = vsprintf( str_replace("?","'%s'",$query), $params );    


        $sql_query = mysql_query($sql_query);    # Perfoming escaped query


    } else {


        $sql_query = mysql_query($query);    # If no params...


    }





    return ($sql_query);


}


?>

presto dot dk at gmail dot com 28-Jan-2010 03:05


If you want to make sure that the ID you're using to do a query is a number, use sprint() of (int) or intval(), but don't use mysql_real_escape_string.



There is no difference between ISO-8859-1's number 10 and UTF-8's number 10.

strata_ranger at hotmail dot com 08-Dec-2009 07:17


There's an interesting quirk in the example #2 about SQL injection:  AND takes priority over OR, so the injected query actually executes as WHERE (user='aidan' AND password='') OR ''='', so instead of returning a database record corresponding to an arbitrary username (in this case 'aidan'), it would actually return ALL database records.  In no particular order.  So an attacker might be able to log in as any account, but not necessarily with any control over which account it is.



Of course a potential attacker could simply modify their parameters to target specific users of interest:



<?php



// E.g. attacker's values

$_POST['username'] = '';

$_POST['password'] = "' OR user = 'administrator' AND '' = '";



// Malformed query

$query = "SELECT * FROM users WHERE user='$_POST[username]' AND password='$_POST[password]'";



echo $query;



// The query sent to MySQL would read:

// SELECT * FROM users WHERE user='' AND password='' OR user='administrator' AND ''='';

// which would allow anyone to gain access to the account named 'administrator'



?>

alan_a_williams [at] hotmail [dot] com 19-Aug-2009 11:17


Just a little something I like to use....





$_GET = array_map('trim', $_GET); 


$_POST = array_map('trim', $_POST); 


$_COOKIE = array_map('trim', $_COOKIE);


$_REQUEST = array_map('trim', $_REQUEST);


if(get_magic_quotes_gpc()):


    $_GET = array_map('stripslashes', $_GET); 


    $_POST = array_map('stripslashes', $_POST); 


    $_COOKIE = array_map('stripslashes', $_COOKIE);


    $_REQUEST = array_map('stripslashes', $_REQUEST);


endif;


$_GET = array_map('mysql_real_escape_string', $_GET); 


$_POST = array_map('mysql_real_escape_string', $_POST); 


$_COOKIE = array_map('mysql_real_escape_string', $_COOKIE);


$_REQUEST = array_map('mysql_real_escape_string', $_REQUEST);





Seems to do the trick ALOT of the time, but I'm going to be honest, it can be a [EDITED] sometimes >_>

Anonymous 02-Aug-2009 10:45


I use the following code in my database connection include file (which is of course called at the start of every page that needs to do some SQL)...


Therefore, all POST and GET vars are automatically escaped before being used anywhere in SQL statements.





<?php


  //This stops SQL Injection in POST vars


  foreach ($_POST as $key => $value) {


    $_POST[$key] = mysql_real_escape_string($value);


  }





  //This stops SQL Injection in GET vars


  foreach ($_GET as $key => $value) {


    $_GET[$key] = mysql_real_escape_string($value);


  }


?>

plgs at ozemail dot com dot au 27-Jul-2009 08:05


Don't forget that if you're using Mysqli (ie, the "improved" Mysql extension) then you need to use the corresponding mysqli function mysqli_real_escape_string().  The parameter order is also different.

Anonymous 13-Jul-2009 03:30


It is because you swapped $key and $item:



Just change this:

<?php

  function mysql_safe ( $item, $key, $type )

  ?>



To: 



<?php 

        function mysql_safe ( $key, $item, $type )

?>



And it will work as expected.

isaacs dot brian dot c at gmail dot com 12-Jul-2009 06:06


I had wanted to see the merits of dynamically and "automatically" applying mysql_real_escape_string() to $_GET and $_POST as arrays rather than manually each time I would type up a query. I used array_walk_recursive() to call my function "mysql_safe" to apply mysql_real_escape_string() to each key of the $_GET and $_POST arrays.





My function is part of a class, and it is called each time I connect to the database to perform a query:





<?php


class MyClass {


        function mysql_safe ( $key, $item, $type )


        {


            switch( $type )


            {            


                case 'get': 


                    if( count( $_GET ) > 0 )


                    {


                        $_GET[$item] = mysql_real_escape_string( $key ); 


                    }


                break;


                case 'post': 


                    if( count( $_POST ) > 0 )


                    {


                        $_POST[$item] = mysql_real_escape_string( $key );


                    }


                break;


            }


        }


        


        function safe_get ( )


        {


            #Flag to only run function once            


            if( $this->get_flag == true ) { return true; }





            array_walk_recursive( $_GET, array( $this, 'mysql_safe' ), 'get' );


            array_walk_recursive( $_POST, array( $this, 'mysql_safe' ), 'post' );


            


            $this->get_flag = true;


        }


}


?>





However, after using this function, I find that it does indeed work, it also creates new $_GET and $_POST values in which $item and $key are swapped. So I end up with $_GET[$item] = $key, as well as $_GET[$key] = $item. I have not yet determined if this is due to the actual coding itself, or my particular method of implementation.





[EDIT BY danbrown AT php DOT net: Contains a bugfix by "Anonymous" on 13-JUL-09 to reorder the user function parameters.]

info at saturnprods dot com 13-Jun-2009 07:37


I always use this function so I don't have to retype over and over the mysql_real_escape_string function.





<?php


function safe($value){


   return mysql_real_escape_string($value);


}


?>





Then, when I am using my code, I simply use:





<?php


$name = safe($_POST["name"]);


$password = safe($_POST["password"]);


?>

kendsnyder at gmail dot com 25-Mar-2009 09:07


<?php



// Here is a simple named binding function for queries that makes SQL more readable:

// $sql = "SELECT * FROM users WHERE user = :user AND password = :password";

// mysql_bind($sql, array('user' => $user, 'password' => $password));

// mysql_query($sql);



function mysql_bind(&$sql, $vals) {

    foreach ($vals as $name => $val) {

        $sql = str_replace(":$name", "'" . mysql_real_escape_string($val) . "'", $sql);

    }

}



?>

Bastiaan Welmers 24-Mar-2008 07:46


This function won't help you when inserting binary data, to me it will get mallformed into the database. Probably UTF-8 combinations will be translated by this function or somewhere else when inserting data when running mysql in UTF-8 mode.



A better way to insert binary data is to transfer it to hexadecimal notation like this example:



<?php

$string = $_REQUEST['string'];

$binary = file_get_contents($_FILE['file']['tmp_name']);



$string = mysql_real_escape_string($string);

$binary_hex = bin2hex($binary);



$query = "INSERT INTO `table` (`key`, `string`, `binary`, `other`) VALUES (NULL, '$string', 0x$binary_hex, '$other')";



?>

Anonymous 03-Mar-2008 06:57


My escape function:





Automatically adds quotes (unless $quotes is false), but only for strings. Null values are converted to mysql keyword "null", booleans are converted to 1 or 0, and numbers are left alone. Also can escape a single variable or recursively escape an array of unlimited depth.





<?php


function db_escape($values, $quotes = true) {


    if (is_array($values)) {


        foreach ($values as $key => $value) {


            $values[$key] = db_escape($value, $quotes);


        }


    }


    else if ($values === null) {


        $values = 'NULL';


    }


    else if (is_bool($values)) {


        $values = $values ? 1 : 0;


    }


    else if (!is_numeric($values)) {


        $values = mysql_real_escape_string($values);


        if ($quotes) {


            $values = '"' . $values . '"';


        }


    }


    return $values;


}


?>

matthijs at yourmediafactory dot com 27-Dec-2007 09:49


In response to Michael D - DigitalGemstones.com: 



Check the example again: sprintf(%d) already does the int conversion for you, so it's both perfectly save as well as more elegant than manually casting.

user at NOSPAM dot example dot com 28-Aug-2007 12:16


if you're doing a mysql wildcard query with


LIKE, GRANT, or REVOKE


you may use addcslashes to escape the string:





<?php


$param = mysql_real_escape_string($param);


$param = addcslashes($param, '%_');


?>

brian dot folts at gmail dot com 06-Sep-2006 04:25


mysql_real_escape_string is a bit annoying when you need to do it over an array.





<?php


function mysql_real_escape_array($t){


    return array_map("mysql_real_escape_string",$t);


}


?>





this one just mysql_real_escape's the whole array.





ex) <?php $_POST=mysql_real_escape_array($_POST); ?>





and then you dont have to worry about forgetting to do this.

kael dot shipman at DONTSPAMIT! dot gmail dot com 18-Jul-2006 08:19


It seems to me that you could avoid many hassels by loading valid database values into an array at the beginning of the script, then instead of using user input to query the database directly, use it to query the array you've created. For example:



<?php

//you still have to query safely, so always use cleanup functions like eric256's

$categories = sql_query("select catName from categories where pageID = ?",$_GET['pageID']);

while ($cts = @mysql_fetch_row($categories)) {

 //making $cts both the name and the value of the array variable makes it easier to check for in the future.

 //obviously, this naming system wouldn't work for a multidimensional array

 $cat_ar[$cts[0]] = $cts[0];

}

...



//user selects sorting criteria

//this would be from a query string like '?cats[]=cha&cats[]=fah&cats[]=lah&cats[]=badValue...', etc.

$cats = $_GET['cats'];



//verify that values exist in database before building sorting query

foreach($cats as $c) {

 if ($cat_ar[$c]) { //instead of in_array(); maybe I'm just lazy... (see above note)

  $cats1[] = "'".mysql_real_escape_string($c)."'";

 }

}

$cats = $cats1;

//$cats now contains the filtered and escaped values of the query string



$cat_query = '&& (category_name = \''.implode(' || category_name = \'',$cats).'\')';

//build a sql query insert

//$cat_query is now "&& (category_name = 'cha' || category_name = 'fah' || category_name = 'lah')" - badValue has been removed

//since all values have already been verified and escaped, you can simply use them in a query

//however, since $pageID hasn't been cleaned for this query, you still have to use your cleaning function

$items = sql_query("SELECT * FROM items i, categories c WHERE i.catID = c.catID && pageID = ? $cat_query", $pageID);

nicolas 30-May-2006 08:38


Note that mysql_real_escape_string doesn't prepend backslashes to \x00, \n, \r, and and \x1a as mentionned in the documentation, but actually replaces the character with a MySQL acceptable representation for queries (e.g. \n is replaced with the '\n' litteral). (\, ', and " are escaped as documented) This doesn't change how you should use this function, but I think it's good to know.

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