TSQL:NULL在";在;条款
我需要在以下情况下过滤记录:TSQL:NULL在";在;条款,sql,sql-server,tsql,sql-server-2008,Sql,Sql Server,Tsql,Sql Server 2008,我需要在以下情况下过滤记录: NotificationRead = 0 || NULL --> IF GetRead = 0 NotificationRead = 1 --> IF GetRead = 1 NotificationRead = 0 || 1 || NULL --> IF GetRead = NULL 以下是我对此使用的查询: DECLARE @GetRead BIT DECLARE @Query VARCHAR(20) SET @GetRead = NULL
NotificationRead = 0 || NULL --> IF GetRead = 0
NotificationRead = 1 --> IF GetRead = 1
NotificationRead = 0 || 1 || NULL --> IF GetRead = NULL
以下是我对此使用的查询:
DECLARE @GetRead BIT
DECLARE @Query VARCHAR(20)
SET @GetRead = NULL
IF @GetRead = 0 SET @Query = '0,NULL'
ELSE IF @GetRead = 1 SET @Query = '1'
ELSE SET @Query = '0,1,NULL'
SELECT * FROM vwNotifications WHERE NotificationRead IN (@Query)
当我在in
子句中提供NULL
时,上述查询基本上失败。
我知道为什么要感谢你
但是,如果我采取该问题答案中建议的方法(使用NotificationRead-in(@Query)或NotificationRead为NULL
),我会在不需要它们的情况下(例如@GetRead=1
您能给我指出正确的方向吗?不,问题是您提供的值是字符串
1 IN (1, 2) -- true.
1 IN ('1, 2') -- false.
请尝试以下方法:
SELECT *
FROM vwNotifications
WHERE (@GetRead = 0 AND (NotificationRead = 0 OR NotificationRead IS NULL))
OR (@GetRead = 1 AND NotificationRead = 1)
OR (@GetRead IS NULL AND (NotificationRead IN (0, 1) OR
NotificationRead IS NULL))
其他人可能有更好的方法,但我会将您的select移到每个“if”语句中,并进行相应的修改
IF @GetRead = 0
SELECT * FROM vwNotifications WHERE NotificationRead IS NULL or NotificationRead = 0
ELSE IF @GetRead = 1
SELECT * FROM vwNotifications WHERE NotificationRead = 1
ELSE
SELECT * FROM vwNotifications WHERE NotificationRead IS NULL or NotificationRead in 0, 1
注意:请不要在生产代码中实际使用SELECT*
。命名您的列。有几个选项:
DECLARE @T TABLE (ID INT IDENTITY(1,1), Notify INT)
DECLARE @GetRead BIT
SET @GetRead = 0
INSERT INTO @T
( Notify )
VALUES ( 0 -- Notify - int
)
INSERT INTO @T
( Notify )
VALUES ( 1 -- Notify - int
)
INSERT INTO @T
( Notify )
VALUES ( NULL -- Notify - int
)
SELECT *
FROM @t t
WHERE @GetRead IS NULL
OR (@GetRead = 0 AND (t.Notify =0 OR t.Notify IS NULL))
OR (@getRead = 1 AND t.Notify = @GetRead)
SELECT *
FROM @t t
WHERE @GetRead IS NULL
OR ISNULL(t.notify, 0) = @GetRead
您可以将SETANSI NULLS添加到查询的顶部。添加NULL后,可以在(NULL)子句中使用
您不能在
中的中使用NULL
,因为NULL
s不能与SQL Server
上下文中的其他值/变量进行比较。对于exmaple,以下语句将不返回任何内容:SELECT*FROM[dbo].[TEST],其中[TestColumn]位于(NULL)
SET ANSI NULLS OFF
SELECT * ......
....
WHERE UserId IN (1, 2, NULL)