mysqli::real_escape_string

mysqli_real_escape_string

(PHP 5)

mysqli::real_escape_string -- mysqli_real_escape_string — Escapes special characters in a string for use in an SQL statement, taking into account the current charset of the connection

说明

面向对象风格

string mysqli::escape_string ( string $escapestr )

string mysqli::real_escape_string ( string $escapestr )

过程化风格

string mysqli_real_escape_string ( mysqli $link , string $escapestr )

This function is used to create a legal SQL string that you can use in an SQL statement. The given string is encoded to an escaped SQL string, taking into account the current character set of the connection.

Caution

Security: the default character set

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

参数

link

仅以过程化样式：由 mysqli_connect() 或 mysqli_init() 返回的链接标识。

escapestr

The string to be escaped.

Characters encoded are NUL (ASCII 0), \n, \r, \, ', ", and Control-Z.

返回值

Returns an escaped string.

范例

Example #1 mysqli::real_escape_string() example

面向对象风格

  <?php
$mysqli  = new  mysqli ( "localhost" ,  "my_user" ,  "my_password" ,  "world" );

 
 if ( mysqli_connect_errno ()) {
     printf ( "Connect failed: %s\n" ,  mysqli_connect_error ());
    exit();
}

 $mysqli -> query ( "CREATE TEMPORARY TABLE myCity LIKE City" );

 $city  =  "'s Hertogenbosch" ;

 
 if (! $mysqli -> query ( "INSERT into myCity (Name) VALUES (' $city ')" )) {
     printf ( "Error: %s\n" ,  $mysqli -> sqlstate );
}

 $city  =  $mysqli -> real_escape_string ( $city );

 
 if ( $mysqli -> query ( "INSERT into myCity (Name) VALUES (' $city ')" )) {
     printf ( "%d Row inserted.\n" ,  $mysqli -> affected_rows );
}

 $mysqli -> close ();
 ?>

过程化风格

  <?php
$link  =  mysqli_connect ( "localhost" ,  "my_user" ,  "my_password" ,  "world" );

 
 if ( mysqli_connect_errno ()) {
     printf ( "Connect failed: %s\n" ,  mysqli_connect_error ());
    exit();
}

 mysqli_query ( $link ,  "CREATE TEMPORARY TABLE myCity LIKE City" );

 $city  =  "'s Hertogenbosch" ;

 
 if (! mysqli_query ( $link ,  "INSERT into myCity (Name) VALUES (' $city ')" )) {
     printf ( "Error: %s\n" ,  mysqli_sqlstate ( $link ));
}

 $city  =  mysqli_real_escape_string ( $link ,  $city );

 
 if ( mysqli_query ( $link ,  "INSERT into myCity (Name) VALUES (' $city ')" )) {
     printf ( "%d Row inserted.\n" ,  mysqli_affected_rows ( $link ));
}

 mysqli_close ( $link );
 ?>

以上例程会输出：

Error: 42000
1 Row inserted.

注释

Note:

For those accustomed to using mysql_real_escape_string() , note that the arguments of mysqli_real_escape_string() differ from what mysql_real_escape_string() expects. The link identifier comes first in mysqli_real_escape_string() , whereas the string to be escaped comes first in mysql_real_escape_string() .

参见

mysqli_set_charset() - 设置默认字符编码
mysqli_character_set_name() - 返回当前数据库连接的默认字符编码

用户评论:

[#1] Anonymous [2015-03-25 21:20:02]

If you wonder why (besides \, ' and ") NUL (ASCII 0), \n, \r, and Control-Z are escaped: it is not to prevent sql injection, but to prevent your sql logfile to get unreadable.

[#2] nmmm at nmmm dot nu [2014-05-01 18:09:26]

Note unlike PDO string escape, MySQLi does not include apostrophes.

So, you probably want something like this:

function escape($s){
$s = $this->mysqli->real_escape_string($s);
return "'$s'";
}

[#3] zanferrari at gmail dot com [2013-11-11 20:27:33]

When I submit data through Ajax I use a little function to reconvert the encoded chars to their original value. After that I do the escaping. Here the function:

   function my_htmlentities($input){
       $string = htmlentities($input,ENT_NOQUOTES,'UTF-8');
       $string = str_replace('€',chr(128),$string);
       $string = html_entity_decode($string,ENT_NOQUOTES,'ISO-8859-15');
       return $string;
   }

G.Zanferrari

[#4] kit dot lester at mail dot com [2013-08-28 23:35:51]

A PHP application I'm working on has many pages which (long story) need to share a PHP API that looks after a MySQL database. Easiest way was to have the app pages AJAX to the API .PHPs.

That means having the JavaScript of the AJAX encodeURIComponent(...) relevant bits of any data to be sent via HTTP POST and GET requests - space as %20 and so on.

But the SQL also needed real_escape_string(...) of the same data.

So I had the issue of whether to do the real_escape_string *before* or *after* encodeURIComponent? in other words in the application PHP or API PHP? Do either of the encodings mangle the other?

The real_escape_string would be "cleaner" in the API, both in principle, and because it needs an instance of mysqli class and there are are unlikely to be instances in the app.

(real_escape_string needs an instance because it's not a *static* function - I don't know why).

But I suspect that "in the API" is the mangle-avoiding place: the JavaScript encode gets undone by the HTTP call to whichever API element, then the element can safely real_escape_string what is to be put into the database.

Comments would be appreciated.

[#5] dave at mausner.us [2011-02-25 07:48:13]

You can avoid all character escaping issues (on the PHP side) if you use prepare() and bind_param(), as an alternative to placing arbitrary string values in SQL statements. This works because bound parameter values are NOT passed via the SQL statement syntax.

[#6] Josef Toman [2010-02-26 06:14:00]

For percent sign and underscore I use this:
<?php $more_escaped = addcslashes($escaped, '%_'); ?>

[#7] tobias_demuth at web dot de [2005-11-10 08:54:07]

Note, that if no connection is open, mysqli_real_escape_string() will return an empty string!

[#8] arnoud at procurios dot nl [2004-10-07 09:05:22]

Note that this function will NOT escape _ (underscore) and % (percent) signs, which have special meanings in LIKE clauses.

As far as I know there is no function to do this, so you have to escape them yourself by adding a backslash in front of them.