Question

场景是我们有两个列表：

A：23,45，g5,33

B：11,12,45，g9

我们希望SQL SERVER中最快的机制来查看A中是否有任何B值，在这个示例中，45是在A中，因此它必须返回true。

解决方案应描述存储列表的方式（CSV，表格等）和比较机制。

每个列表相对较小（每个列表平均10个值），但是进行了多次比较（写入次数很少，读取次数很多）

Answer 1

我仍然对核心理念感到困惑......但这是一个比逗号分隔列表更好的简单解决方案。当然，创建索引会使速度更快。它比循环更快。

var id = Property.N(p => p.PropertyId) ?? 0;

分道

declare @table table (id char(4), v varchar(256))
insert into @table
values
('A','23'),
('A','45'),
('A','g5'),
('A','33'),
('B','11'),
('B','12'),
('B','45'),
('B','g9')


select distinct
    base.v
    --,base.*
    --,compare.*
from 
    @table base
inner join
    @table compare
    on compare.v = base.v
    and compare.id <> base.id

<强> USING THIS FUNCTION

declare @table table (id char(4), v varchar(256))
insert into @table
values
('A','23,45,g5,33'),
('B','11,12,45,g9')

;with cte as(
    select 
        t.ID
        ,base.Item
    from 
        @table t
        cross apply dbo.DelimitedSplit8K(t.v,',') base)

select
    t.Item
from
    cte t
inner join
    cte x on 
    x.Item = t.Item
    and x.id <> t.id
where
    t.id = 'A'

Answer 2

如果您遇到分隔字符串，请考虑以下事项：

示例：

Declare @YourTable Table ([ColA] varchar(50),[ColB] varchar(50)) Insert Into @YourTable Values ('23,45,g5,33' ,'11,12,45,g9') ,('no,match' ,'found,here') Select * from @YourTable A Cross Apply ( Select Match=IsNull(sum(1),0) From [dbo].[udf-Str-Parse-8K](ColA,',') B1 Join [dbo].[udf-Str-Parse-8K](ColB,',') B2 on B1.RetVal=B2.RetVal ) B

<强>返回

ColA ColB Match 23,45,g5,33 11,12,45,g9 1 no,match found,here 0

UDF如果有兴趣

CREATE FUNCTION [dbo].[udf-Str-Parse-8K] (@String varchar(max),@Delimiter varchar(25)) Returns Table As Return ( with cte1(N) As (Select 1 From (Values(1),(1),(1),(1),(1),(1),(1),(1),(1),(1)) N(N)), cte2(N) As (Select Top (IsNull(DataLength(@String),0)) Row_Number() over (Order By (Select NULL)) From (Select N=1 From cte1 a,cte1 b,cte1 c,cte1 d) A ), cte3(N) As (Select 1 Union All Select t.N+DataLength(@Delimiter) From cte2 t Where Substring(@String,t.N,DataLength(@Delimiter)) = @Delimiter), cte4(N,L) As (Select S.N,IsNull(NullIf(CharIndex(@Delimiter,@String,s.N),0)-S.N,8000) From cte3 S) Select RetSeq = Row_Number() over (Order By A.N) ,RetVal = LTrim(RTrim(Substring(@String, A.N, A.L))) From cte4 A ); --Orginal Source http://www.sqlservercentral.com/articles/Tally+Table/72993/ --Select * from [dbo].[udf-Str-Parse-8K]('Dog,Cat,House,Car',',') --Select * from [dbo].[udf-Str-Parse-8K]('John||Cappelletti||was||here','||')

Answer 3

根据之前的回答，我认为它应该是这样的：

declare @table table (id char(4), v varchar(256))
insert into @table
values
('A','23'),
('A','45'),
('A','g5'),
('A','33'),
('B','11'),
('B','12'),
('B','45'),
('B','g9')


if exists( select count(1)
        from 
            @table base
        inner join
            @table compare
            on compare.v = base.v
            and base.id='A' and compare.id='B') 
 print 'true'
 else
 print 'false'

id，v或v，id的索引取决于数据的增长

将数据存储在两个CSV字符串与两个db表中，以便进行最快速的比较

3 个答案: