连接多个 case when 语句的结果

Question

我想在满足条件时显示建立在 when 语句上的多个字符串的串联。如下 ：

select

case
  when T1.Field is not null then 'T1,' 
  when T2.Field is not null then /*last results*/ + 'T2,' 
  when T3.Field is not null then /*last results*/ + 'T3,'
end


from T1 
left outer join T2 on ...
left outer join T3 on ...

Answer 1

终于发现了......我之前没有意识到这是可能的：

select

  case when T1.Field is not null then 'T1,' else '' end
+ case when T2.Field is not null then 'T2,' else '' end
+ case when T3.Field is not null then 'T3,' else '' end as result

from T1 
left outer join T2 on ...
left outer join T3 on ...