Php Mysql选择命令问题

Question

I want to check some data if ti's remain on database. Example: in my form there are two form field. 1) url 2) name. So i want to check if session user have already this 'url' and 'name' in the database then it's must be show error message. Here is just few mysql code..

<?php
$url        = mysql_real_escape_string(trim($_POST['url']));
$name       = mysql_real_escape_string(trim($_POST['name']));
$uname  = $_SESSION['uname'];

$check_add  = mysql_query("SELECT * FROM add_fav WHERE url ='$url' AND name= '$name' 
AND uname = '$uname' ");

$num        =  mysql_num_rows($check_add); 

if($num > 0)
            $err[] = "Already exist";
?>

But It's doesn't check. May be it's my query problem.
Thanks in Advance:)

Answer 1

Try and debug your script to make sure you actually have values for your select statement... echo out your variables to make sure they have data... check it right before you do your select statement, if they are coming up empty make sure that you instantiate the db connection before running mysql_real_escape_string or it won't work...