Home » Is filter_var sufficient to sanitise integer input for PHP-based MySQL queries?

Is filter_var sufficient to sanitise integer input for PHP-based MySQL queries?


I myself would create a function for that task, possibly in a static class somewhere,

public static function escape_int($i) {
    $sanitised = intval($i); 
    if( '_' . $sanitised . '_' === '_' . $i . '_'  && $sanitised > 0 ) {
        return $sanitised;
    throw new IntegerEscapeException( $i, $sanitised );
    return "ENOINT"; # Wont Run This, but I prepare for the impossible. 

try { 
    $sql="SELECT * FROM TABLE_NAME WHERE idUser = " . DB::escape_int( $userid ); 
} catch( IntegerEscapeException $e ) { 
    die ( "You shot the sherif!" ); # bad example.

This is good because if I discover my sanitation method reeks I can fix it later.

A much simpler and easier-to-read method that I use is this:

$sql="SELECT * FROM TABLE_NAME WHERE idUser = " . intval($idUser);

It attempts to convert $idUser to an integer and on failure returns 0 which none of my tables have as real id’s. (So I know the input was invalid if it evaluates to 0.)

To answer your actual question, no that won’t leave any holes open. I suggest getting rid of the repetitive code though:

$idUserIN_filtered = filter_var($idUserIN, FILTER_VALIDATE_INT);

if (isset($idUserIN) 
    && $idUserIN_filtered 
    && 0 < $idUserIN_filtered
    ) {
      $sql="SELECT * FROM TABLE_NAME WHERE idUser = ".$idUser_filtered;
} else {
  // handle invalid data

This is all you need

if ($idUser = filter_var($idUserIN, FILTER_VALIDATE_INT)) {
      $sql="SELECT * FROM TABLE_NAME WHERE idUser = ".$idUser;
} else {
  // handle invalid data


if ($idUser = filter_input(INPUT_POST, 'userId', FILTER_VALIDATE_INT)) {

Alternatively you can check if its invalid in MVC.

if (!$idUser = filter_var($idUserIN, FILTER_VALIDATE_INT)) {
      throw new InputParameterException('UserId');
//else its valid

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