Find MySQL table with matching value and update field

Question

I created a registration verification system where the user gets an email with a link to verify their account. When the link is clicked it takes them to a PHP page below:

<?php
$passkey = trim(mysqli_real_escape_string($connection, $_GET['passkey']));

$query = "UPDATE pims SET com_code=NULL WHERE com_code='$passkey' UNION ALL UPDATE dms SET com_code=NULL WHERE com_code='$passkey' UNION ALL UPDATE users SET com_code='$passkey'";

$result = mysqli_query($connection, $query);
    if (!result) {
        die("Database query failed: " . mysqli_error($result));
    }

if (mysqli_num_rows($result) == 0) {
    echo '<div>Sorry. Something went wrong! Please contact the site admin at <a href="mailto:support@domain.com">support@domain.com</a> for assistance.</div>';

} else {
    echo '<div>Your account is now active. You may now <a href="login.php">Log in</a></div>';
}
?>

I want to set the com_code to NULL, but first I need to find the user in 1 of 3 tables (pims, dms, and users) by matching the $passkey variable.

This is not working. Any suggestions?

---

UPDATE:

I fixed the code as Sean pointed out:

$query = "UPDATE pims SET com_code=NULL WHERE com_code='$passkey' 
UNION ALL UPDATE dms SET com_code=NULL WHERE com_code='$passkey' 
UNION ALL UPDATE users SET com_code=NULL WHERE com_code='$passkey'";

But, it's still not working.

---

UPDATE:

I updated the code again like so:

<?php
    $passkey = mysqli_real_escape_string($connection, $_GET['passkey']);

    $query = "UPDATE pims, dms, users SET pims.com_code=NULL, dms.com_code=NULL, users.com_code=NULL WHERE pims.com_code='$passkey' AND dms.com_code='$passkey' AND users.com_code='$passkey'";

    $result = mysqli_query($connection, $query);
        if (mysqli_affected_rows ($connection) > 0) {
            echo '<div>Your account is now active. You may now <a href="login.php">Log in</a></div>';
        } else {
            echo '<div>ERROR MESSAGE<br><br>Sorry, something went wrong!<br><br>Please contact the site admin at <a href="mailto:support@domain.com">support@domain.com</a> for assistance.</div>';
    }

    mysqli_close($connection);
?>

But for some reason it just won't connect.

---

UPDATE:

So, I decided to go with 3 queries like this:

<?php
    $passkey = mysqli_real_escape_string($connection, $_GET['passkey']);

    $query = "UPDATE pims SET com_code=NULL WHERE com_code='{$passkey}'";

    $result = mysqli_query($connection, $query);
        if (mysqli_affected_rows ($connection) <= 0) {

            $query = "UPDATE dms SET com_code=NULL WHERE com_code='{$passkey}'";

            $result = mysqli_query($connection, $query);
                if (mysqli_affected_rows ($connection) <= 0) {

                    $query = "UPDATE users SET com_code=NULL WHERE com_code='{$passkey}'";

                    $result = mysqli_query($connection, $query);
                        if (mysqli_affected_rows ($connection) <= 0) {
                            echo '<div> ERROR MESSAGE<br><br>Sorry, something went wrong!<br><br>Please contact the site admin at <a href="mailto:support@domain.com">support@domain.com</a> for assistance.</div>';
                        } else {
                            echo '<div>Your account is now active. You may now <a href="login.php">Log in</a></div>';
                        }
                } else {
                    echo '<div>Your account is now active. You may now <a href="login.php">Log in</a></div>';
                }
        } else {
            echo '<div>Your account is now active. You may now <a href="login.php">Log in</a></div>';
        }

    mysqli_close($connection);
?>

It works, but it seems very slow. Any suggestions for improvements would be appreciated.

Answer 1

Try doing it all in 1 query, instead of doing a UNION ALL

UPDATE 
 pims,dms,users
SET
 pims.com_code=NULL, dms.com_code=NULL, users.com_code=NULL
WHERE 
 pims.com_code='$passkey'
AND
 dms.com_code='$passkey'
AND
 users.com_code='$passkey'

SQL Fiddle example - http://sqlfiddle.com/#!2/d0464d/1