Quick Quetion

[Kayzio]

Currently I have the following code:

$Check = mysql_query("SELECT * FROM user_friends WHERE id='$ID' AND friend_id='$FriendID'");
$CheckNumRows = mysql_num_rows($Check);
$CheckReverse = mysql_query("SELECT * FROM user_friends WHERE id='$FriendID' AND friend_id='$ID'");
$CheckReverseNumRows = mysql_num_rows($CheckReverse);
if ($CheckNumRows == 0 && $CheckReverseNumRows == 0) {
    // do something
} 

I would like to know if the following code is basically the same thing as above but using only 1 sql statement:

$Check = mysql_query("SELECT * FROM user_friends WHERE (id='$ID' OR id='$FriendID') AND (friend_id='$ID' OR friend_id = '$FriendID')");
$CheckNumRows = mysql_num_rows($Check);
if ($CheckNumRows == 0) {
    // do something
} 

[mithra62]

Wow. My head hurts trying to figure this out.

Technically, it looks like it should be comparable. Realistically, it's probably not a good idea to use the second approach though. Since:

"SELECT * FROM user_friends WHERE (id='$ID' OR id='$FriendID') AND (friend_id='$ID' OR friend_id = '$FriendID')" 

uses an OR type you run the risk of false positives. If you're worried about system resources with two queries you could work it out like

"SELECT count(COLUMN) FROM TABLE" 

Hope that helps.

[wonshikee]

Currently I have the following code:

$Check = mysql_query("SELECT * FROM user_friends WHERE id='$ID' AND friend_id='$FriendID'");
$CheckNumRows = mysql_num_rows($Check);
$CheckReverse = mysql_query("SELECT * FROM user_friends WHERE id='$FriendID' AND friend_id='$ID'");
$CheckReverseNumRows = mysql_num_rows($CheckReverse);
if ($CheckNumRows == 0 && $CheckReverseNumRows == 0) {
    // do something
} 

I would like to know if the following code is basically the same thing as above but using only 1 sql statement:

$Check = mysql_query("SELECT * FROM user_friends WHERE (id='$ID' OR id='$FriendID') AND (friend_id='$ID' OR friend_id = '$FriendID')");
$CheckNumRows = mysql_num_rows($Check);
if ($CheckNumRows == 0) {
    // do something
} 

1) Your syntax is wrong, you can't take a string of a query and pass it to mysql_num_rows, you need to call mysql_query first.

2) Otherwise your second query - while bit confusing is correct.

I would think it makes more sense - following with the first query to order it like this..

( id = '$id' AND friendID = '$friendID' ) OR ( id = '$friendID' AND friendID = '$id' ) 

This makes more sense to me anyway.

[Kayzio]

Thanks for the help. I don't know why I didn't think of doing it the way you showed me wonshikee.