PDO::quote

(PHP 5 >= 5.1.0, PECL pdo >= 0.2.1)

PDO::quote Quotes a string for use in a query.

Descrierea

public string PDO::quote ( string $string [, int $parameter_type = PDO::PARAM_STR ] )

PDO::quote() places quotes around the input string (if required) and escapes special characters within the input string, using a quoting style appropriate to the underlying driver.

If you are using this function to build SQL statements, you are strongly recommended to use PDO::prepare() to prepare SQL statements with bound parameters instead of using PDO::quote() to interpolate user input into an SQL statement. Prepared statements with bound parameters are not only more portable, more convenient, immune to SQL injection, but are often much faster to execute than interpolated queries, as both the server and client side can cache a compiled form of the query.

Not all PDO drivers implement this method (notably PDO_ODBC). Consider using prepared statements instead.

Precauţie

Security: the default character set

The character set must be set either on the server level, or within the database connection itself (depending on the driver) for it to affect PDO::quote(). See the driver-specific documentation for more information.

Parametri

string

The string to be quoted.

parameter_type

Provides a data type hint for drivers that have alternate quoting styles.

Valorile întoarse

Returns a quoted string that is theoretically safe to pass into an SQL statement. Returns FALSE if the driver does not support quoting in this way.

Exemple

Example #1 Quoting a normal string

<?php
$conn 
= new PDO('sqlite:/home/lynn/music.sql3');

/* Simple string */
$string 'Nice';
print 
"Unquoted string: $string\n";
print 
"Quoted string: " $conn->quote($string) . "\n";
?>

Exemplul de mai sus va afișa:

Unquoted string: Nice
Quoted string: 'Nice'

Example #2 Quoting a dangerous string

<?php
$conn 
= new PDO('sqlite:/home/lynn/music.sql3');

/* Dangerous string */
$string 'Naughty \' string';
print 
"Unquoted string: $string\n";
print 
"Quoted string:" $conn->quote($string) . "\n";
?>

Exemplul de mai sus va afișa:

Unquoted string: Naughty ' string
Quoted string: 'Naughty '' string'

Example #3 Quoting a complex string

<?php
$conn 
= new PDO('sqlite:/home/lynn/music.sql3');

/* Complex string */
$string "Co'mpl''ex \"st'\"ring";
print 
"Unquoted string: $string\n";
print 
"Quoted string: " $conn->quote($string) . "\n";
?>

Exemplul de mai sus va afișa:

Unquoted string: Co'mpl''ex "st'"ring
Quoted string: 'Co''mpl''''ex "st''"ring'

Vedeți de asemenea

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User Contributed Notes 4 notes

up
9
mirv
1 year ago
When converting from the old mysql_ functions to PDO, note that the quote function isn't exactly the same as the old mysql_real_escape_string function. It escapes, but also adds quotes; hence the name I guess :-)

After I replaced mysql_real_escape_string with $pdo->quote, it took me a bit to figure out why my strings were turning up in results with quotes around them. I felt like a fool when I realized all I needed to do was change ...\"".$pdo->quote($foo)."\"... to ...".$pdo->quote($foo)."...
up
5
col dot shrapnel at gmail dot com
1 year ago
One have to understand that string formatting has nothing to do with identifiers.
And thus string formatting should NEVER ever be used to format an identifier ( table of field name).
To quote an identifier, you have to format it as identifier, not as string.
To do so you have to

- Enclose identifier in backticks.
- Escape backticks inside by doubling them.

So, the code would be:
<?php
function quoteIdent($field) {
    return
"`".str_replace("`","``",$field)."`";
}
?>
this will make your identifier properly formatted and thus invulnerable to injection.

However, there is another possible attack vector - using dynamical identifiers in the query may give an outsider control over fields the aren't allowed to:
Say, a field user_role in the users table and a dynamically built INSERT query based on a $_POST array may allow a privilege escalation with easily forged $_POST array.
Or a select query which let a user to choose fields to display may reveal some sensitive information to attacker.

To prevent this kind of attack yet keep queries dynamic, one ought to use WHITELISTING approach.

Every dynamical identifier have to be checked against a hardcoded whitelist like this:
<?php
$allowed 
= array("name","price","qty");
$key = array_search($_GET['field'], $allowed));
if (
$key == false) {
    throw new
Exception('Wrong field name');
}
$field = $db->quoteIdent($allowed[$key]);
$query = "SELECT $field FROM t"; //value is safe
?>
(Personally I wouldn't use a query like this, but that's just an example of using a dynamical identifier in the query).

And similar approach have to be used when filtering dynamical arrays for insert and update:

<?php
function filterArray($input,$allowed)
{
    foreach(
array_keys($input) as $key )
    {
        if ( !
in_array($key,$allowed) )
        {
             unset(
$input[$key]);
        }
    }
    return
$input;
}
//used like this
$allowed = array('title','url','body','rating','term','type');
$data = $db->filterArray($_POST,$allowed);
// $data now contains allowed fields only
// and can be used to create INSERT or UPDATE query dynamically
?>
up
0
php at deobald dot org
6 years ago
Note that this function just does what the documentation says: It escapes special characters in strings.

It does NOT - however - detect a "NULL" value. If the value you try to quote is "NULL" it will return the same value as when you process an empty string (-> ''), not the text "NULL".
up
-1
milosdj at gmail dot com
8 months ago
This function also converts new lines to \r\n
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