SQL syntax: passing variable to SQL select query

Question

I'm trying to pass variables into the select query. Quer is below

$Email = $_POST["Email"];
$Username = $_POST["User_Name"];
$FirstName = $_POST["First_Name"];
$Password = $_POST["Password"];


$CreateTable = "CREATE TABLE IF NOT EXISTS "+$Username+" (
address_id int(11) NOT NULL 
) ENGINE=MyISAM AUTO_INCREMENT=9 DEFAULT CHARSET=utf8;" ;

But the table wasn't creating. Where I missed?

Thanks your valuable time.

Answer 1

As you would not be able to use prepared statements with this type of query you should perhaps attempt to remove potentially harmful characters from the supplied user input.

$email = filter_input( INPUT_POST, 'Email', FILTER_SANITIZE_STRING, FILTER_FLAG_STRIP_LOW | FILTER_FLAG_STRIP_HIGH );
$username = filter_input( INPUT_POST, 'User_Name', FILTER_SANITIZE_STRING, FILTER_FLAG_STRIP_LOW | FILTER_FLAG_STRIP_HIGH );
$firstname = filter_input( INPUT_POST, 'First_Name', FILTER_SANITIZE_STRING, FILTER_FLAG_STRIP_LOW | FILTER_FLAG_STRIP_HIGH );
$password = filter_input( INPUT_POST, 'Password', FILTER_SANITIZE_STRING, FILTER_FLAG_STRIP_LOW | FILTER_FLAG_STRIP_HIGH );


/* Strip any non alphanumeric charachters and replace space with underscore */
$username = preg_replace('@^[\da-z]$@i','', str_replace( ' ', '_', $username ) );


$sql = "CREATE TABLE IF NOT EXISTS `{$username}` (
    address_id int(11) NOT NULL 
) ENGINE=MyISAM DEFAULT CHARSET=utf8;";

$db=new mysqli( $dbhost, $dbuser, $dbpwd, $dbname );
$db->query( $sql );

Answer 2

You are using '+' symbol to connect two string (which will not work in php).

You should use '.' to connect two strings.

See answer : How to combine two strings together in PHP?

Your SQL statement should look like this :

$CreateTable = "CREATE TABLE IF NOT EXISTS ".$Username." (
address_id int(11) NOT NULL 
) ENGINE=MyISAM AUTO_INCREMENT=9 DEFAULT CHARSET=utf8;" ;

BTW, It's not recommended to execute sensitive queries such as creating (NOR DELETING) tables within your php script.

Answer 3

You should check your PHP file. And try

$tableUser = "CREATE TABLE IF NOT EXISTS ".$Username."(
index int(11) NOT NULL
) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=utf8;" ;