Easy sql statement not working HELP

[Anon]

I don't understand why this simple code will not give me the desired effect. All I want to do is check the database to see if a field(registration) has something in it. If it does then print a message, otherwise include another file. This code does not work. It always prints the message even if the field is blank. I can't figure out why? Is there a better way to do this?

Thanks.

<?php
$sql= "SELECT registration FROM login WHERE id = $session[id] and registration is not null";
$result = mysql_query($sql);
if (mysql_num_rows($result) > 0)
print "You are part of a group course registration.";
else
include ("link.php");
?>

[[deleted]]

You are probably checking for the wrong condition.

registration IS NOT NULL

means that the field contains "something" but that "something" can also be an empty string.

What you probably want to to check is

and registration !=""

that will make sure that 'registration' contains at least one character.

[toma42]

You would do well to change your string to be
$sql= "SELECT registration FROM login WHERE id = {$session[id]} and registration is not null";

So php will know for sure that $session[id] is a variable.