Hilfe benötigte eine Set-Abfrage für die Suche nach den besten Noten von den Studenten erhielten für das Schreiben

Question

ich die Tabelle unten habe

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 

Der gewünschte Ausgang

Id  Name  Sub1  Sub2  Sub3  Sub4 

3  Name3       100     

4  Name4  80        80 

5  Name5  80   70      

6  Name6          80 

werden soll, was ich bisher getan haben

ist

;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 

, die mir die Ausgabe als

schenkt

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 

Hilfe benötigt.

Wie kann ich auch die Anzahl der CTEs reduzieren?

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