SQL分组的问题

Question

SELECT STR_TO_DATE(d1.redeemTime,'%Y-%m-%d') redeemTime,SUM(redeemMoney) redeemMoney,STATUS
FROM dingpackredeemlist
GROUP BY redeemTime,status

为什么用别名不行要写成
SELECT STR_TO_DATE(d1.redeemTime,'%Y-%m-%d') redeemTime,SUM(redeemMoney) redeemMoney,STATUS
FROM dingpackredeemlist
GROUP BY STR_TO_DATE(d1.redeemTime,'%Y-%m-%d'),status

Answer 1

分组是根据你查询表(原始表)的字段来的，不是你查出表的字段