SELECT
discount_price = 
ROUND((db_product_discount.h_output_discount_ls*db_product.h_output_price),2)
FROM db_product,db_product_discount
WHERE db_product.h_id=db_product_discount.h_id
AND db_product.h_id='.7800126050022000000'
输出的结果为:20.900000000000
而我想要的是结果后四舍五入后小数点保留两位;
请问这个SQL 怎么写?谢谢