MySQL Error Occurred

Error Message:
1021: Disk full (/var/mysqltmp/#sql_5cab_4.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")

SQL:
SELECT cubecart_cats_idx.cat_id, cubecart_cats_idx.productId, productCode, quantity, description, image, weight, price, pkr_list_price,amz_price,amz_list_price,name,sale_price,prod_flag,status FROM cubecart_cats_idx INNER JOIN cubecart_inventory ON cubecart_cats_idx.productId = cubecart_inventory.productId WHERE cubecart_cats_idx.cat_id = '46' AND cubecart_inventory.status = 0 and prod_flag=0 GROUP BY cubecart_inventory.productId order by productId DESC