逗号分隔值（CSV）参数过滤

Question

需要有关如何改进我的SQL脚本以获得更好性能的帮助。 dbo.Products表有百万行。我很犹豫要用动态SQL重写它。谢谢！

DECLARE 
    @Brand varchar(MAX) = 'Brand 1, Brand 2, Brand 3', 
    @ItemCategory varchar(MAX) = 'IC1, IC2, IC3, IC4, IC5' 

--will return all records if params where set to @Brand = NULL, @ItemCategory = NULL 

SELECT 
    [Brand], 
    SUM([Amount]) AS [Amount] 
FROM dbo.Products (NOLOCK) 
LEFT JOIN [dbo].[Split](@Brand, ',') FilterBrand ON Brand = [FilterBrand].[Items] 
LEFT JOIN [dbo].[Split](@ItemCategory, ',') FilterItemCategory ON ItemCategory = [FilterItemCategory].[Items] 
WHERE 
    (@Brand IS NULL OR (@Brand IS NOT NULL AND [FilterBrand].[Items] IS NOT NULL)) AND 
    (@ItemCategory IS NULL OR (@ItemCategory IS NOT NULL AND [FilterItemCategory].[Items] IS NOT NULL)) 
GROUP BY 
    [Brand] 

下面是拆分表值函数，我在网上找到：

CREATE function [dbo].[Split] 
(
    @String  varchar(8000), 
    @Delimiter char(1) 
) 
RETURNS @Results TABLE (Items varchar(4000)) 
AS 
BEGIN 
    IF (@String IS NULL OR @String = '') RETURN 

    DECLARE @i int, @j int 

    SELECT @i = 1 

    WHILE @i <= LEN(@String) 
     BEGIN 
      SELECT @j = CHARINDEX(@Delimiter, @String, @i) 

      IF @j = 0 
       BEGIN 
        SELECT @j = len(@String) + 1 
       END 

      INSERT @Results SELECT RTRIM(SUBSTRING(@String, @i, @j - @i)) 

      SELECT @i = @j + LEN(@Delimiter) 
     END 

    RETURN 
END 

Answer 1

以下解决方案与使用进行功能

Declare @IDs Varchar(100) 
SET @IDs = '2,4,6' 

Select IsNull(STUFF((Select ', '+ CAST([Name] As Varchar(100)) From [TableName] 
Where CharIndex(','+Convert(Varchar,[ID])+',', ','+@IDs+',')> 0 
For XML Path('')),1,1,''),'') As [ColumnName] 

Answer 2

这里是我使用的功能。我也有另一个包装这个返回数值，我也觉得很有帮助。

编辑：对不起，至于如何提高查询性能，我平时值分成表变量，并执行我加入到但这可能不会改变你的表现，只是你的可读性。我在表现方面唯一能看到的就是你双重检查你的连接是否产生任何东西。在两个表上有两个有条件的左连接，你实际上无法获得更好的性能。它基本上归结为当时的索引。

(@Brand IS NULL OR [FilterBrand].[Items] IS NOT NULL) 

功能：

ALTER FUNCTION [dbo].[fn_SplitDelimittedList] 
(
    @DelimittedList varchar(8000), 
    @Delimitter varchar(20) 
) 
RETURNS 
@List TABLE 
(
    Item varchar(100) 
) 
AS 
BEGIN 
    DECLARE @DelimitterLength INT 
    SET @DelimitterLength = LEN(@Delimitter) 

    -- Tack on another delimitter so we get the last item properly 
    set @DelimittedList = @DelimittedList + @Delimitter 

    declare @Position int 
    declare @Item varchar(500) 

    set @Position = patindex('%' + @Delimitter + '%' , @DelimittedList) 
    while (@Position <> 0) 
    begin 
     set @Position = @Position - 1 
     set @Item = LTRIM(RTRIM(left(@DelimittedList, @Position))) 

     INSERT INTO @List (Item) VALUES (@Item) 

     set @DelimittedList = stuff(@DelimittedList, 1, @Position + @DelimitterLength, '') 
     set @Position = patindex('%' + @Delimitter + '%' , @DelimittedList) 
    end 

    RETURN 
END 

Answer 3

嘿只是尝试我都没有使用任何while循环here.And只是用这个来代替你的分割功能，并使用关口，以匹配LEFT JOIN创建的分割功能。

ALTER function dbo.SplitString(@inputStr varchar(1000),@del varchar(5)) 
RETURNS @table TABLE(col varchar(100)) 
As 
BEGIN 

DECLARE @t table(col1 varchar(100)) 
INSERT INTO @t 
select @inputStr 

if CHARINDEX(@del,@inputStr,1) > 0 
BEGIN 
;WITH CTE as(select ROW_NUMBER() over (order by (select 0)) as id,* from @t) 
,CTE1 as (
select id,ltrim(rtrim(LEFT(col1,CHARINDEX(@del,col1,1)-1))) as col,RIGHT(col1,LEN(col1)-CHARINDEX(@del,col1,1)) as rem from CTE 
union all 
select c.id,ltrim(rtrim(LEFT(rem,CHARINDEX(@del,rem,1)-1))) as col,RIGHT(rem,LEN(rem)-CHARINDEX(@del,rem,1)) 
from CTE1 c 
where CHARINDEX(@del,rem,1)>0 
) 

INSERT INTO @table 
select col from CTE1 
union all 
select rem from CTE1 where CHARINDEX(@del,rem,1)=0 
END 
ELSE 
BEGIN 
INSERT INTO @table 
select col1 from @t 
END 


RETURN 

END 


DECLARE @Brand varchar(MAX) = 'Brand 1,Brand 2,Brand 3', 
     @ItemCategory varchar(MAX) = ' IC1 A ,IC2 B , IC3 C, IC4 D' --'IC1, IC2, IC3, IC4, IC5' 

select * from dbo.SplitString(@ItemCategory,',')