sql server 将逗号分隔值拆分为列

Question

我尝试将 csv 拆分为单独的列

样本数据

PAR_COLUMN  PERIOD  VALUE       mul_query
----------  ------  ---------   ---------
1           601     10.134542   10.134542
1           602     20.234234   10.134542*20.234234
1           603     30.675643   10.134542*20.234234*30.675643
1           604     40.234234   10.134542*20.234234*30.675643*40.234234
2           601     10.345072   10.345072
2           602     20.345072   10.345072*20.345072
2           603     30.345072   10.345072*20.345072*30.345072
2           604     40.345072   10.345072*20.345072*30.345072*40.345072

预期结果:

PAR_COLUMN  period   value     (No column name)    (No column name)    (No column name)    (No column name)
----------  ------  ---------  ----------------    ----------------    ----------------     ---------------
1           601     10.134542  10.134542            1                   1                   1
1           602     20.234234  10.134542            20.234234           1                   1
1           603     30.675643  10.134542            20.234234           30.675643           1
1           604     40.234234  10.134542            20.234234           30.675643           40.234234
2           601     10.345072  10.345072            1                   1                   1
2           602     20.345072  10.345072            20.345072           1                   1
2           603     30.345072  10.345072            20.345072           30.345072           1
2           604     40.345072  10.345072            20.345072           30.345072           40.345072

我尝试过这样的。它可以工作，但当数据很大时速度很慢。有没有更好的替代方案。

declare @sql varchar(max) = ''
set @sql =
';WITH Split_Names 
AS
(
    SELECT PAR_COLUMN,
    mul_query,period,
    CONVERT(XML,''<Names><name>''  
    + REPLACE(mul_query,''*'', ''</name><name>'') + ''</name></Names>'') AS xmlname
      FROM #finals
)
SELECT PAR_COLUMN,
    period,
'


declare @start int =1 ,@count int 
set @count = (select (max(period) - min(period))+1 from #finals)
while @start <= @count
begin 
set @sql +=concat( 'isnull(xmlname.value(''/Names[1]/name[',@start,']'',''float''),1) , ')
 set @start+=1
end
set @sql =left(@sql,len(@sql)-1)
set @sql+= ' FROM Split_Names'

exec( @sql)

注意:问题是不将CSV转换为单个行。我正在尝试将 CSV 转换为单独的列 基本上我正在尝试计算 Value 列中的RUNNING 乘法

>

Answer 1

动态解决这个问题，使用DSQL在结果中相应地添加更多列。

--create split function
CREATE FUNCTION [dbo].[SO_Split]
(
    @List nvarchar(2000),
    @SplitOn nvarchar(5)
) 
RETURNS @RtnValue table
(

    Id int identity(1,1),
    Value nvarchar(100)
)
AS 
BEGIN
While (Charindex(@SplitOn,@List)>0)
Begin
Insert Into @RtnValue (value)
Select
    Value = ltrim(rtrim(Substring(@List,1,Charindex(@SplitOn,@List)-1)))
    Set @List =Substring(@List,Charindex(@SplitOn,@List)+len(@SplitOn),len(@List))
End
    Insert Into @RtnValue (Value)
    Select Value = ltrim(rtrim(@List))
    Return
END

--below is the dynamic solution for this problem
declare @sql nvarchar(3000) = 'select *'
declare @cnt int = 1
declare @rowNum int = (select max(a) from (select(select max(id) as id_max from dbo.so_split(mul_query,'*')) as a from #test) as b)

while(@cnt <= @rowNum)
begin
    set @sql = @sql + N', ISNULL((select value from dbo.so_split(mul_query,''*'') where id = '+cast(@cnt as nvarchar(5))+N'),''1'')'
    set @cnt = @cnt + 1
end

set @sql = @sql + N' from #test'

exec sp_executesql @sql

结果附在下面。