php-doc-en/reference/mysql/functions/mysql-escape-string.xml

<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.10 $ -->
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  <refentry id="function.mysql-escape-string">
   <refnamediv>
    <refname>mysql_escape_string</refname>
    <refpurpose>
     Escapes a string for use in a mysql_query.
    </refpurpose>
   </refnamediv>
   <refsect1>
    <title>Description</title>
    <methodsynopsis>
     <type>string</type><methodname>mysql_escape_string</methodname>
     <methodparam><type>string</type><parameter>unescaped_string</parameter></methodparam>
    </methodsynopsis>
    <para>
     This function will escape the <parameter>unescaped_string</parameter>,
     so that it is safe to place it in a <function>mysql_query</function>.
    </para>
    <note>
     <simpara>
      <function>mysql_escape_string</function> does not escape
      <literal>%</literal> and <literal>_</literal>.
     </simpara>
     <simpara>
      This function is identical to <function>mysql_real_escape_string</function> except that
      <function>mysql_real_escape_string</function> takes a connection handler and escapes the
      string according to the current character
      set. <function>mysql_escape_string</function> does not take a
      connection argument and does not respect the current charset setting.  
     </simpara>
    </note>
    <para>
     <example>
      <title><function>mysql_escape_string</function> example</title>
      <programlisting role="php">
<![CDATA[
<?php
$item = "Zak's Laptop";
$escaped_item = mysql_escape_string($item);
printf("Escaped string: %s\n", $escaped_item);
?>
]]>
      </programlisting>
      <para>
       The above example would produce the following output:
      </para>
      <screen>
<![CDATA[
Escaped string: Zak\'s Laptop
]]>
      </screen>
     </example>
    </para>
    <para>
     <note>
      <simpara>
       This function has been deprecated since PHP 4.3.0.
       Do not use this function. Use <function>mysql_real_escape_string</function>
       instead.
      </simpara>
     </note>
    </para>
    <para>
     See also
     <function>mysql_real_escape_string</function>,
     <function>addslashes</function> and the
     <link linkend="ini.magic-quotes-gpc">magic_quotes_gpc</link>
     directive.
    </para>
   </refsect1>
  </refentry>

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- mysql_escape_string calls MySQL's library function of the same name, which prepends slashes to the following characters: NUL (\x00), \n, \r, \, ', " and \x1a.

- AddSlashes escapes NUL, ', " and \. 

$query = "SELECT * FROM adresses WHERE name='$name' AND private='N'";

mysql_query($query);
?>

Without mysql_escape_string a user could set name to "' OR 1=1 OR ''='"

effectively leading to the query:
SELECT * FROM adresses WHERE name='' OR 1=1 OR ''='' AND private='N'