TSQL - 動態數據查詢

Question

示例數據

表1

Id Column 
1 J1 
2 J3 
3 J2 
4 J2 
5 J1 

表2

RecId J1  J2  J3 
1  1  NULL NULL 
2  1  2  NULL 
3  NULL 3  NULL 
4  NULL 2  NULL 
5  1  NULL NULL 

我需要這個結果

Id RecId Column Value 
1 1  J1  1 
2 2  J3  NULL 
3 3  J2  3 
4 4  J2  2 
5 5  J1  1 

Answer 1

使用此代碼：

declare @Table1 as table(id int ,column1 nvarchar(10)) 

insert into @Table1(Id ,column1) values(1 ,N'J1') 
insert into @Table1(Id ,column1) values(2 ,N'J3') 
insert into @Table1(Id ,column1) values(3 ,N'J2') 
insert into @Table1(Id ,column1) values(4 ,N'J2') 
insert into @Table1(Id ,column1) values(5 ,N'J1') 

declare @Table2 as table (RecId int ,J1 int ,J2 int ,J3 int) 

insert into @Table2(RecId ,J1 ,J2 ,J3)values(1 ,1 ,NULL ,NULL) 
insert into @Table2(RecId ,J1 ,J2 ,J3)values(2 ,1 ,2 ,NULL) 
insert into @Table2(RecId ,J1 ,J2 ,J3)values(3 ,NULL ,3 ,NULL) 
insert into @Table2(RecId ,J1 ,J2 ,J3)values(4 ,NULL ,2 ,NULL) 
insert into @Table2(RecId ,J1 ,J2 ,J3)values(5 ,1 ,NULL ,NULL) 


select t1.id ,t2.RecId ,t1.column1 
     ,(Case t1.column1 
     when N'J1' then t2.J1 
     when N'J2' then t2.J2 
     when N'J3' then t2.J3 
     else NULL end) As Value 
From @Table1 As t1 
inner join @Table2 As t2 ON t1.id = t2.RecId