Question

我下面有一张桌子

declare @t table(bucket bigint null)

insert into @t select 1 union all select 2 union all select -1 union all select 5

现在让我编写以下查询（按存储桶0过滤-所有值都将出现）

declare @Bucket bigint = 0 –filter by 0

select * from @t
where 1=1
AND (@Bucket is Null or @Bucket ='' or bucket=@Bucket)

Result
1
2
-1
5

但是，如果我用2或其他任何值过滤Bucket，我将正确获得结果

declare @Bucket bigint = 2 –filter by 2
select * from @t
where 1=1
AND (@Bucket is Null or @Bucket ='' or bucket=@Bucket)

Result
2

如果我将其过滤为null或空白，则会得到正确的结果

declare @Bucket bigint = '' –filter by ''

select * from @t
where 1=1
AND (@Bucket is Null or @Bucket ='' or bucket=@Bucket)

Result
1
2
-1
5

为什么桶0会出现这种情况？以及如何解决？

Answer 1

您可以尝试将@Bucket bigint = NULL的默认值使用@Bucket。

因为NULL意味着未知

或者您可以设置一个值，该值不应在bucket列中为默认值。

declare @Bucket bigint = NULL

select * 
from @t
where (@Bucket is Null or bucket = @Bucket)

注意

但是如果@Bucket bigint为bigint，则不应为''

修改

CREATE TABLE T(
   Bucket bigint
);

declare @Bucket bigint = 0

INSERT INTO T VALUES (1);
INSERT INTO T VALUES (2);
INSERT INTO T VALUES (-1);
INSERT INTO T VALUES (5);
INSERT INTO T VALUES (0);


select * from T
where  (@Bucket is Null or (@Bucket ='' and @Bucket <> 0)  or bucket=@Bucket)

Answer 2

已修复

declare @t table(bucket bigint);

INSERT INTO @t VALUES (1);
INSERT INTO @t VALUES (2);
INSERT INTO @t VALUES (-1);
INSERT INTO @t VALUES (5);
INSERT INTO @t VALUES (0);

declare @Bucket bigint = 0 --filter by 0

select * from @t
where 1=1
AND (@Bucket is Null or cast(@Bucket as nvarchar) = '' or bucket=@Bucket)

如何为显示的查询正确应用过滤器？

2 个答案: