视图内容如下:
CREATE VIEW [dbo].[view_zy_allpatient]
AS
SELECT *, 'z' AS flag
FROM zy_actpatient
UNION ALL
SELECT *, 'c'AS flag
FROM zy_inactpatient
GO
查询方法1
SELECT * FROM view_zy_allpatient
此时返回的 flag 为null
查询方法1
SELECT *, 'z' AS flag
FROM zy_actpatient
UNION ALL
SELECT *, 'c'AS flag
FROM zy_inactpatient
此时返回的 flag 为z或者flag
重建视图后用方法一查询正常,哪位大侠给讲讲为什么???