假设有表(UserTB)：

1、Union（不允许重复）

SELECT  *
FROM    dbo.UserTB
WHERE   deptId IN ( 1, 3 )
UNION
SELECT  *
FROM    dbo.UserTB
WHERE   deptId IN ( 1, 2 )

2、Union All（允许重复）

SELECT  *
FROM    dbo.UserTB
WHERE   deptId IN ( 1, 3 )
UNION ALL
SELECT  *
FROM    dbo.UserTB
WHERE   deptId IN ( 1, 2 )