在Union中比较查询在sql

Question

嗨程序员！ 我得比较联合查询的选择查询

我的代码是这样的：

  select emp_id,type from 
      (
       select emp_id,'leave' as type 
       from tbl_emp_info 
       where emp_id like'5_2' or emp_id like '602' 
      ) as t1 
      union 
      select emp_id,type from 
      (
       select emp_id,'weekend'as type 
       from tbl_emp_off_info 
       where emp_id like'6_2' 
      ) t2 t1.emp_id!=t2.emp_id 

我需要比较这两种选择查询

 As i need the result like 

      EMP_ID  TYPE 

      512  leave 
      612  weekend    

但不喜欢

  EMP_ID  TYPE 


      512  leave 
      612  leave 
      612  weekend    

请帮我一下

Answer 1

也许这会适合你（SQL Server 2005及更高版本）。

;WITH t1 AS 
(
    SELECT emp_id, 'leave' AS [type] 
    FROM tbl_emp_info 
    WHERE emp_id LIKE '5_2' OR emp_id LIKE '602' 
) 
, t2 AS 
(
    SELECT emp_id, 'weekend' AS [type] 
    FROM tbl_emp_info 
    WHERE emp_id LIKE '6_2' 
) 
SELECT emp_id, [type] 
FROM t1 
WHERE emp_id NOT IN (SELECT emp_id FROM t2) 
UNION 
SELECT emp_id, [type] 
FROM t2 

对于SQL Server 2000，你需要复制的WHERE子句中的一种：

SELECT emp_id, 'leave' AS [type] 
FROM tbl_emp_info 
WHERE (emp_id LIKE '5_2' OR emp_id LIKE '602') 
AND NOT (emp_id LIKE '6_2') 
UNION 
SELECT emp_id, 'weekend' AS [type] 
FROM tbl_emp_info 
WHERE (emp_id LIKE '6_2')