如果sql server中的语句如何从子查询中获取值

Question

我尝试从不同的表中获取结果。 如果name是1111则SELECT * FROM TABLE 1 如果name是2222则SELECT * FROm TABLE 2

SELECT CASE 

WHEN type='111111'

THEN (SELECT * FROM db1)
ELSE (SELECT * FROM db2)
FROM db_name

问题在哪里？

Answer 1

尝试如下：

SELECT 
CASE 
  WHEN COLUMN1='XYZ' THEN (SELECT SINGLE_COL FROM DB1)
  ELSE (SELECT SINGLE_COL FROM DB1) 
END 
FROM TABLE_NAME

内部查询必须返回单个值。

Answer 2

这将给你答案

Select db1.* from db1 join db_name on 1=1 where db_name = '1111111'
union all
Select db2.* from db2 join db_name on 1=1 where db_name <> '1111111'