Question

以下是我的表数据

 Mat   Phy Chem
 20 30  40
 25 35  35
 45 30  30
 45 40  35

我想在一行中检索所有三列中的前三行。

O / P

 Mat  Phy Chem
 45   40   40
 25   35   35
 20   30   30

我使用过以下查询但未成功，请帮助...

Select distinct top 3 max(mat) from studata group by mat order by max(mat) desc
Union all
Select distinct top 3 max(phy) from studata group by phy order by max(phy) desc
Union all
Select distinct top 3 max(chem) from studata group by chem order by max(chem) desc

Answer 1

WITH    q AS
        (
        SELECT  *,
                ROW_NUMBER() OVER (ORDER BY mat DESC) AS rn_mat,
                ROW_NUMBER() OVER (ORDER BY phy DESC) AS rn_phy,
                ROW_NUMBER() OVER (ORDER BY chem DESC) AS rn_chem
        FROM    mytable
        )
SELECT  q_mat.mat, q_phy.phy, q_chem.chem
FROM    q q_mat
JOIN    q q_phy
ON      q_phy.rn_phy = q_mat.rn_mat
JOIN    q q_chem
ON      q_chem.rn_chem = q_phy.rn_phy
WHERE   q_mat.rn_mat <= 3

Answer 2

这有用吗？

select distinct top 3 Mat
from studata
order by Mat desc

select distinct top 3 Phy
from studata
order by Phy desc

select distinct top 3 Chem
from studata
order by Chem desc

你可能遇到问题的原因是因为max是一个函数（它只返回1个东西）所以Select distinct top 3 max(mat)是无意义的。

多列上的Sql Server Max函数？

2 个答案: