ヘルプは、私は以下の表を持って

Question

学生によって得られた最高点を見つけるためのセット・ベースのクエリを記述するために必要に

declare @t table 
(id int identity, name varchar(50),sub1 int,sub2 int,sub3 int,sub4 int) 

insert into @t 
select 'name1',20,30,40,50 union all 
select 'name2',10,30,40,50 union all 
select 'name3',40,60,100,50 union all 
select 'name4',80,30,40,80 union all 
select 'name5',80,70,40,50 union all 
select 'name6',10,30,40,80 

所望の出力がどうあるべきか

として私に出力を与えている

;with cteSub1 as 
(
    select rn1 = dense_rank() over(order by sub1 desc),t.id,t.name,t.sub1 from @t t 
) 
,cteSub2 as 
(
    select rn2 = dense_rank() over(order by sub2 desc),t.id,t.name,t.sub2 from @t t 
) 
,cteSub3 as 
(
    select rn3 = dense_rank() over(order by sub3 desc),t.id,t.name,t.sub3 from @t t 
) 
,cteSub4 as 
(
    select rn4 = dense_rank() over(order by sub4 desc),t.id,t.name,t.sub4 from @t t 
) 
select x1.id,x2.id,x3.id,x4.id ,x1.sub1,x2.sub2,x3.sub3,x4.sub4 from (select c1.id,c1.sub1 from cteSub1 c1 where rn1 =1) as x1 
full join (select c2.id,c2.sub2 from cteSub2 c2 where rn2 =1)x2 
on x1.id = x2.id 
full join (select c3.id,c3.sub3 from cteSub3 c3 where rn3 =1)x3 
on x1.id = x3.id 
full join (select c4.id,c4.sub4 from cteSub4 c4 where rn4 =1)x4 
on x1.id = x4.id 

です

id id id id sub1 sub2 sub3 sub4 
5 5 NULL NULL 80 70 NULL NULL 
4 NULL NULL 4 80 NULL NULL 80 
NULL NULL 3 NULL NULL NULL 100 NULL 
NULL NULL NULL 6 NULL NULL NULL 80 

ヘルプが必要です。

また、CTEの数を減らすにはどうすればよいですか？

Answer 1

WITH cte1 
    AS (SELECT * 
     FROM @t UNPIVOT (grade FOR sub IN (sub1, sub2, sub3, sub4))AS unpvt) 
, 
    cte2 
    AS (SELECT *,Rank() OVER (PARTITION BY sub ORDER BY grade DESC) rn 
     FROM cte1) 
SELECT * 
FROM cte2 PIVOT(MAX (grade) FOR sub IN (sub1, sub2, sub3, sub4)) AS pvt 
WHERE rn = 1