MySQL Error Occurred

Error Message:
1021: Disk full (/var/mysqltmp/#sql_34b1_21.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")

SQL:
SELECT cubecart_multicat_idx.id,cubecart_multicat_idx.img,cubecart_multicat_idx.productId ,cubecart_inventory.productId,cubecart_inventory.productCode, cubecart_inventory.description,cubecart_inventory.image,cubecart_inventory.price,cubecart_inventory.name,cubecart_inventory.cat_id , cubecart_inventory.amz_price , cubecart_inventory.amz_list_price , cubecart_inventory.sale_price ,cubecart_inventory.weight ,cubecart_inventory.status , cubecart_inventory.prod_flag FROM `cubecart_multicat_idx` inner join cubecart_inventory on cubecart_multicat_idx.productId=cubecart_inventory.productId where cubecart_multicat_idx.img='347227' and cubecart_inventory.cat_id>0 and cubecart_inventory.status=0 and cubecart_inventory.prod_flag=0 GROUP by cubecart_inventory.productId ORDER BY cubecart_multicat_idx.id DESC