如何为呈现的查询正确应用过滤器？

Question

我有一张桌子如下

declare @t table(bucket bigint null)

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

现在让我编写下面的查询（按 Bucket 0 过滤 - 所有值都来了）

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

但如果我按 2 或任何其他值过滤 Bucket，我会正确得到结果

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

Result
2

如果我按 null 或空白过滤，我会得到正确的结果

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 会有这种行为？又该如何解决？

Answer 1

您可以尝试使用@Bucket bigint = NULL 作为@Bucket 的默认值。

因为NULL意味着不知道

或者您可以设置一个不应在bucket 列中作为默认值的值。

declare @Bucket bigint = NULL

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

注意

但如果 @Bucket bigint 是 bigint，它不应该是 ''

---

编辑

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)