Question

I’ve tried everything, but nothing works.. Even in an other code I wrote, it works. But for some reason it won’t now.

I want to join two tables where the ID = userID. When I load the page, I get this error:

Warning: mysql_fetch_array(): supplied argument is not a valid MySQL
result resource in
/home/ynxwleus/domains/mustseenmovies.nl/public_html/films/userinfo.php
on line 17

Is there anyone who can help me with this problem?

Code:

$userID = $_SESSION['s_userID'];
        echo $userID;
        $query = "SELECT userID, userName, userFrontname, userSurname, filmID 
        FROM users
        JOIN seenIt
        ON users.userID = seenIt.userID 
        WHERE (userID ='$userID')";

        $res = mysql_query($query);
                while ($row = mysql_fetch_array($res)) {
                    echo $row['userName'];
                    echo $row['userFrontname'];
                    echo $row['userSurname'];
                    echo $row['filmID'];
                }

Thanks in advanced!

Answer 1

Your where clause needs an alias:

    WHERE (users.userID ='$userID')

Your select clause also needs an alias on the userId:

    SELECT users.serID, userName, userFrontname, userSurname, filmID

In fact, it is a really good idea to ALWAYS use aliases:

SELECT u.userID, u.userName, u.userFrontname, u.userSurname, si.filmID 
FROM users u join
     seenIt si
    ON u.userID = si.userID 
WHERE u.userID ='$userID'

The original query has syntax errors, because the SQL engine does not know which userID is being referred to. Oh, you are thinking “that’s obvious because on clause specifies that the values are the same.” Well, humans are smarter than SQL compilers, at least when it comes to common sense.