MySQL Error Occurred

Error Message:
3: Error writing file '/var/mysqltmp/MYeXjiBd' (Errcode: 28 "No space left on device")

SQL:
SELECT I.name, I.productId, I.price, I.sale_price, I.price-I.sale_price AS saving FROM cubecart_inventory AS I, cubecart_category AS C WHERE C.cat_id = I.cat_id AND (C.cat_desc != '##HIDDEN##' OR C.cat_desc IS NULL) AND I.disabled = '0' AND I.price > I.sale_price AND I.sale_price > 0 AND I.cat_id > 0 ORDER BY saving DESC