Error - Problem in Product Selection

Hello:
I am new to MySQL. I am getting this error because of this query written for me. Can you pls advice me how I can better write this query.

Problem in Product Selection: The SELECT would examine more than MAX_JOIN_SIZE rows; check your WHERE and use SET SQL_BIG_SELECTS=1 or SET SQL_MAX_JOIN_SIZE=# if the SELECT is okay.


$qry = "Select tblproducts.productcode, tblproductattributes.attribid, Min(tblproductattributes.oneprice) AS price, tblproducts.productid, tblproducts.productcode, tblproducts.smallimage, tblproducts.title, tblproducts.sef, tblproductattributes.productcode, tblproductassignment.productcode, tblproductassignment.categorycode, tblproducts.isactive
from tblproductattributes, tblproductassignment, tblproducts
where tblproductassignment.categorycode='$catidd' and tblproductassignment.productcode=tblproducts.produ ctcode and tblproducts.isactive = 'A'
group by tblproducts.productcode";
$result = mysql_query($qry) or die("Problem in Product Selection: " . @mysql_error());