使用 WHERE 子句将复杂的 QUERY 查询到 VIEW

Question

我有一个如下所示的计划表：

我想要一个 SQL，它可以让我选择每个 artikelnr、日期和 jahr_kw（日历周），如果条目为空，它将采用前一个日期的条目。这是这样的：

select distinct artikelnr
            , datum
            , jahr_kw
            , first_value(menge) over (partition by artikelnr, jahr_kw 
                              order by (case when menge is not null then 1 else 2 end), datum desc
                             ) as imputed_Jahr_KW

from test_table
where datum between '2021-02-01' and '2021-03-01' -- for example

注意 where 子句。

现在我的问题是，我如何查看这个查询，我可以在 where 子句中选择日期（基准）？

Answer 1

也许表值函数是最好的

示例

CREATE FUNCTION [dbo].[tvf_SomeName](@Date1 date,@Date2 date)
Returns Table 
As
Return (  
    
select distinct artikelnr
            , datum
            , jahr_kw
            , first_value(menge) over (partition by artikelnr, jahr_kw 
                              order by (case when menge is not null then 1 else 2 end), datum desc
                             ) as imputed_Jahr_KW

from test_table
where datum between @Date1 and @Date2


);

用法

Select * From [dbo].[tvf_SomeName]('2021-02-01','2021-03-01')

Answer 2

您可以根据需要使用索引视图。

需要如下形式的索引，查询会很快

CREATE TABLE Yourdb.test_table(artikelnr int,datum Date,jahr_kw smallint,menge INT )
GO

    CREATE VIEW Yourdb.testview
    WITH SCHEMABINDING
       AS  
          select distinct artikelnr
            , datum
            , jahr_kw
            , first_value(menge) over (partition by artikelnr, jahr_kw 
                              order by (case when menge is not null then 1 else 2 end),   datum desc
                             ) as imputed_Jahr_KW

         from test.test_table
    GO

GO

    --Create an index on the view.
    CREATE  INDEX IDX_V1   ON Yourdb.testview (datum);
    GO
GO

db小提琴here

用法

SELECT * FROM Yourdb.testview WHERE where datum between '2021-02-01' and '2021-03-01'

Answer 3

删除distinct 并简单地创建视图

create view SomeView
as
select        artikelnr
            , datum
            , jahr_kw
            , first_value(menge) over (partition by artikelnr, jahr_kw 
                              order by (case when menge is not null then 1 else 2 end), datum desc
                             ) as imputed_Jahr_KW

from test_table

由于datum 是由视图投影而没有应用任何查询运算符，因此您可以从视图外部有效地对其进行过滤。

select *
from SomeView
where datum between '2021-02-01' and '2021-03-01' 

EG：

drop table if exists test_table

create table test_table
(
  artikelnr int,
  datum varchar(20),
  jahr_kw int, 
  menge int
)
insert into test_table
values 
 (1,'01.Jan',1,10),
 (1,'01.Jan',2,7),
 (1,'01.Jan',3,1),
 (1,'02.Jan',1,null),
 (1,'02.Jan',2,5),
 (1,'02.Jan',3,2),
 (1,'03.Jan',1,null),
 (1,'03.Jan',2,4),
 (1,'03.Jan',3,3),
 (1,'04.Jan',1,null),
 (1,'04.Jan',2,9),
 (1,'04.Jan',3,4),
 (1,'01.Jan',1,20),
 (1,'01.Jan',2,10),
 (1,'01.Jan',3,4),
 (1,'02.Jan',1,30),
 (1,'02.Jan',2,20),
 (1,'02.Jan',3,3),
 (1,'03.Jan',1,null),
 (1,'03.Jan',2,15),
 (1,'03.Jan',3,2)
 

 
 go

create or alter view vT
as
 select artikelnr
            , datum
            , jahr_kw
            , first_value(menge) over (partition by artikelnr, jahr_kw 
                              order by (case when menge is not null then 1 else 2 end), datum desc
                             ) as imputed_Jahr_KW

from test_table

go

 select distinct artikelnr
            , datum
            , jahr_kw
            , first_value(menge) over (partition by artikelnr, jahr_kw 
                              order by (case when menge is not null then 1 else 2 end), datum desc
                             ) as imputed_Jahr_KW

from test_table
where datum between '01.Jan' and '03.Jan' -- for example


select *
from vt 
where datum between '01.Jan' and '03.Jan' -- for example