Question

我有一个像下面这样的sql语句。如何在不使用union关键字的情况下将单行（code = 0，desc = 1）添加到此sql语句的结果中？感谢。

select code, desc
from material 
where material.ExpireDate ='2010/07/23'

Answer 1

您始终可以为您的表创建一个视图，该视图本身使用UNION关键字

CREATE VIEW material_view AS SELECT code, desc, ExpireDate FROM material UNION SELECT '0', '1', NULL;
SELECT code, desc FROM material_view WHERE ExpireDate = '2010/07/23' OR code = '0';

Answer 2

 WITH material   AS
 (
 SELECT * 
 FROM 
      (VALUES (2, 'x', '2010/07/23'), 
              (3, 'y', '2009/01/01'), 
              (4, 'z', '2010/07/23')) vals (code, [desc], ExpireDate)
 )

SELECT 
     COALESCE(m.code,x.code) AS code, 
     COALESCE(m.[desc],x.[desc]) AS [desc]
FROM material m
FULL OUTER JOIN (SELECT 0 AS code, '1' AS [desc] ) x ON 1=0
WHERE m.code IS NULL OR m.ExpireDate ='2010/07/23'

给出

code        desc
----------- ----
2           x
4           z
0           1

Answer 3

由于你不想使用联合或视图，我建议在材质表中添加一个虚拟行（代码= 0，desc = 1和ExpireDate通常不会选择的东西 - 例如，1900年1月1日） - 然后使用如下的查询：

select code, desc
from material 
where material.ExpireDate ='2010/07/23' or 
    material.ExpireDate ='1900/01/01'

通常，联盟将是我的首选。

如何在不使用union的情况下编写Sql语句？

3 个答案: