Problems with SQL Helper Function

I'm working on a module, and I need to do an SELECT QUERY with an INNER JOIN. Here is what I have:

$table = "tblcustomfieldsvalues";
$fields = "fieldid,fieldname";
$where = array(
	"relid"=>array("sqltype"=>"LIKE","value"=>$params['serviceid']),
);
$sort = "fieldid";
$sortorder = "ASC";
$limits = "0,2";
$join = "tblcustomfields ON tblcustomfields.id=tblcustomfieldsvalues.fieldid";
$result = select_query($table,$fields,$where,$sort,$sortorder,$limits,$join);

There are two custom fields for this product, and their values occupy two rows in the tblcustomfieldsvalues table. This query should result in two records, with fieldid (from tblcustomfieldvalues) and fieldname (from tblcustomfields) for each. However, $result always comes up null.

Anyone out there have any ideas?

Ok, for anyone who's interested, I figured it out. I think the problem stems from the field "relid" being present in both tables. Therefore, I added the table name to the $where variable as follows:

   $where = array( 
       "tblcustomfieldsvalues.relid"=>array("sqltype"=>"LIKE","value"=>$params['serviceid']), 
   );

It seems to have done the trick.