Question

How can i pass a “NULL” or “String” in a sql query.

For example (city is optional and NULL can be used in mysql)

<?php
$var = !empty($_POST['city']) ? $_POST['city'] : NULL;
$query = mysql_query("INSERT INTO table VALUES('".$_POST['firstname']."','".$var."')");
?>

This is not working, beacuse NULL and ‘NULL'(as String) are not the same for mysql.

Answer 1

Don’t surround NULL with quotes in the query:

$var = !empty($_POST['city']) ? ( "'" . $_POST['city'] . "'") : 'NULL';
$query = mysql_query("INSERT INTO table VALUES('".$_POST['firstname']."',".$var.")");

Now, when $_POST['city'] is not specified, your query will look something like this:

INSERT INTO table VALUES('nickb',NULL)