多列上的Sql Server Max函數？

Question

下面是我的表數據

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

我要檢索單一行的所有三列前3位的最大行數。

O/P

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

我用下面的查詢，但不成功，請幫助...

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

工作的呢？

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 

你可能會得到一個問題的原因是因爲max是函數（它僅會返回1周的事情），所以Select distinct top 3 max(mat)是無稽之談。