My delete function doesn't work! (PM System)

[Shahlin]

I'm done with the whole PM system. Only thing that's not working is the delete conversation feature. Here's my delete_conversation function :

function delete_conversation($conversation_id){
	$conversation_id = (int)$conversation_id;
	
	$sql = "SELECT DISTINCT `conversation_deleted`
			FROM `conversations_members`
			WHERE `user_id` != {$_SESSION['user_id']}
			AND `conversation_id` = {$conversation_id}";
	
	$result = mysql_query($sql);
	
	if(mysql_num_rows($result) === 1 && mysql_result($result, 0) == 1){
		mysql_query("DELETE FROM `conversations` WHERE `conversation_id` = {$conversation_id}");
		mysql_query("DELETE FROM `conversations_members` WHERE `conversation_id` = {$conversation_id}");
		mysql_query("DELETE FROM `conversations_messages` WHERE `conversation_id` = {$conversation_id}");
	} else {
		$sql = "UPDATE `conversations_members`
				SET `conversation_deleted` = 1 
				WHERE `conversation_id` = {$conversation_id}
				AND `user_id` = {$_SESSION['user_id']}";
				
		mysql_query($sql);

	}
}

[ExtremeGaming]

if(mysql_num_rows($result) === 1

One to many ='s here

[jacek]

What is not working about it ? What does happen compared to what you expect ?