Friend system

[doddsey_65]

For my friend system usernames are stored in a table (f_username) along with the username of the friend (f_friend_username).

 

Im trying to display the friends of a user on their profile but the users username can be in either the f_username column or the f_friend_username column.

 

So i have this query but it returns the same result twice. Is there a better way around this? I thought about a conditional ON statement but don't know if it's possible.

 

$sql = "SELECT f.*, u.u_avatar
                FROM ".Asf_Db::$prefix."friends f
                JOIN ".Asf_Db::$prefix."users u
                ON (
                    f.f_username = u.u_username
                    OR
                    f.f_friend_username = u.u_username
                )
                WHERE (
                    f_username = ?
                    OR 
                    f_friend_username = ?
                )
                AND f_confirmed = ?";
                
        $sth = Asf_Core::$db->prepare($sql);
        $sth->execute(array(
            $username,
            $username,
            1
            )
        ) or die(Asf_Core::$db->error($sth, $sql));

 

[requinix]

Just stick the WHERE conditions into the JOIN's:

SELECT f.*, u.u_avatar
FROM friends f
JOIN users u ON (
f.f_username = u.u_username AND f.f_friend_username = $username
OR f.f_friend_username = u.u_username AND f.f_username = $username
)
AND f.f_confirmed = 1

You might want a DISTINCT too if your friendslisting thing doesn't already check for an existing pair when adding friends.

[fenway]

Yes, but use parenthesis or your ORs and ANDs won't work.

[requinix]

Yes, but use parenthesis or your ORs and ANDs won't work.

:-\ But ANDs are higher than ORs, so the way I have it should be fine.

 

And for the record the f_confirmed thing was supposed to be in a WHERE, but I suppose it's okay where it is.

[fenway]

Yes, but use parenthesis or your ORs and ANDs won't work.

:-\ But ANDs are higher than ORs, so the way I have it should be fine.

I sincerely hope you don't rely on the arbitrary order-of-operations that way -- you should be able to add an arbitrary new expression without breaking everything.

 

Add the 4 characters, you'll thank me later.  Order-of-operations shouldn't exist.

[Pandemikk]

Fenway has a point, it can be a headache to alter your existing query and spend hours looking for why the results aren't showing up as expected only to realize its because of that pesky new AND / OR clause messing up your logic. I speak from personal less-than-a-week-ago experience.

 

It also looks nicer. Nicer looking code = Super A+ bro guy;

[requinix]

Fair enough, but I always write sets of conditions in the same way that makes it easy for me to tell where my ANDs and ORs are. Believe me, if I thought there would be ambiguity then I would be more explicit.

(cond OR cond) AND
cond AND
(cond OR cond)

cond AND cond AND cond
OR cond AND cond AND cond
OR cond AND cond AND cond

But to each their own.