Question

我有3个表格，其中包含以下架构：

表1列：ID MsgNum Msg 表2列：ID MsgNum SystemId 表3列：ID MsgNum IncidentNum

我希望表1中的所有项目都包含MsgNum，其范围从表2和表3中选择。

从表2中，使用以下SQL获取MsgNum的可能值：

SELECT Table2.MsgNum from Table2 WHERE SystemId = 'Sys-0001'

和表3，

SELECT Table3.MsgNum from Table3 WHERE IncidentNumber = 'Incident-0001'

现在，我想使用从前2个SELECT语句中获取的MsgNum值的组合来获取Table1中的相应行，如下所示：

SELECT * from Table1 where MsgNum IN ( SELECT Table2.MsgNum from Table2 WHERE SystemId = 'Sys-0001'  OR  SELECT Table3.MsgNum from Table3 WHERE IncidentNumber = 'Incident-0001')

但是这个SQL使用Interactive SQL失败了。我做错了什么？

Answer 1

为什么不使用EXISTS

SELECT * from Table1 t1 
where EXISTS ( SELECT t2.MsgNum from Table2 t2 
 WHERE t2.SystemId = 'Sys-0001' AND t2.MsgNum = t1.MsgNum)
OR  EXISTS (SELECT t3.MsgNum from Table3 t3 
 WHERE t3.IncidentNumber = 'Incident-0001' AND t3.MsgNum = t1.MsgNum)

Answer 2

使用UNION命令将两个查询放在一起

SELECT * from Table1 where MsgNum IN (
 SELECT Table2.MsgNum from Table2 WHERE SystemId = 'Sys-0001'
   UNION
   SELECT Table3.MsgNum from Table3 WHERE IncidentNumber = 'Incident-0001')
)

Answer 3

你的意思是UNION？

SELECT * 
from Table1 
where MsgNum IN 
( 
SELECT Table2.MsgNum from Table2 WHERE SystemId = 'Sys-0001'  
UNION 
SELECT Table3.MsgNum from Table3 WHERE IncidentNumber = 'Incident-0001'
)

SQL：从两个不同的表中获取“IN”运算符的可能值

3 个答案: