Doing more than one thing.......

I have a script that adds fields to a database, but if a URL is added twice i would like it to tell them it is already there. I was thinking of doing a:
SELECT * FROM table WHERE url = '$url'
and if it cant find it then it adds it and if it can find it it informs the person....but i cant quite get it right. Can someone help? I use php (just so you know)

thanks,
Scott

Consider making the URL field a primary key in the table so duplicates may not be added. If it cannot be made the primary key, then make it a unique key and include the appropriate error checks/error messages in your PHP script when inserting new data in the DB table.

> alter table table_name add UNIQUE url_ind (URL);

<?
$query="insert into table_name values('$a', '$b', '$c', '$URL'...etc.";

$result=mysql_query($query, $mysql_link);

if($result){ print"Info added.";}

else
{
$errno=mysql_errno($mysql_link);
$error=mysql_error($mysql_link);
print"ERROR: $errno - $error";
}
?>

Something like that...