[RESOLVED] undefined variable

purple

I've just created a query to see if users are an admin or not.
I'm not sure if the query does what it's supposed to, but it's saying i have an undefined variable $a.
Who and where do I need to define the $a?

if (isset($_SESSION['user_id']) AND (substr($_SERVER['PHP_SELF'], -10) != 'logout.php')) 
    { 
        echo '<a href="logout.php">Logout</a><br /> 
              <a href="link.php">link</a><br />'; 
        $query = "SELECT user_id FROM users WHERE admin='$a'"; 
        $result = mysql_query($query); 
        if (mysql_num_rows($result) == 1) 
        { 
            echo '<a href="morelinks.php">more links</a><br />'; 
        } 
    } 
    else 
    { 
        //Not logged in. 
        echo '<a href="register.php">Register</a><br /> 
        <a href="login.php">Login</a><br /> 
        <a href="forgot_password.php">Forgot Password</a><br />'; 
    }

halojoy

Only you would know where and for what.

The 'admin' field. What is the data in such a column?
A number or some word or what?

This query you use.
Do you know what it is for?
What it is supposed to find when admin='$a'.
And why search for it?

$query = "SELECT user_id FROM users WHERE admin='$a'";

purple

The default value is 0 for no they are not an administrator and 1 for yes, they are
I'm displaying additional links for administrators.

dagon

purple;10943538 wrote:
The default value is 0 for no they are not an administrator and 1 for yes, they are
I'm displaying additional links for administrators.

in that case WHERE admin='1' would find an admin. what was $a suppose to be?

johanafm

Don't query the database for this all the time. When you check their login credentials, also check if they are admin or not and keep that as session data. Then all you have to do on each page request

if ($_SESSION['is_admin']) {
	// ...
}