sql-server-2008t-sqlssmscsvcross-apply

Using CROSS APPLY for more than one column


Day #3 with SQL Server.

I am trying to combine 2 columns of delimited data into one output from a Table Valued Function. Here is my data:

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I would like the data to be processed and placed into a table in the following format:

enter image description here

I am currently trying to use this CROSS APPLY TSQL statement, but I don't know what I'm doing.

USE [Metrics]
INSERT INTO dbo.tblSplitData(SplitKey, SplitString, SplitValues)
SELECT d.RawKey, c.*, e.*
FROM dbo.tblRawData d
CROSS APPLY dbo.splitstringcomma(d.DelimitedString) c, dbo.splitstringcomma(d.DelimitedValues) e

My research on CROSS APPLY has broad context, and I don't understand how it should be applied in this scenario. Do I need a subquery with an additional CROSS APPLY and a join to combine the returns from the two Table Valued Functions?

Here is the split function I was using originally (I can't remember the author to credit them):

CREATE FUNCTION [dbo].[splitstring] ( @stringToSplit VARCHAR(MAX), @Delimiter CHAR(1))
RETURNS
 @returnList TABLE ([Name] [nvarchar] (500))
AS
BEGIN

 DECLARE @name NVARCHAR(255)
 DECLARE @pos INT

 WHILE CHARINDEX(@Delimiter, @stringToSplit) > 0
 BEGIN
  SELECT @pos  = CHARINDEX(@Delimiter, @stringToSplit)  
  SELECT @name = SUBSTRING(@stringToSplit, 1, @pos-1)

  INSERT INTO @returnList 
  SELECT @name

  SELECT @stringToSplit = SUBSTRING(@stringToSplit, @pos+1, LEN(@stringToSplit)-@pos)
 END

 INSERT INTO @returnList
 SELECT @stringToSplit

 RETURN
END

Edit & Revised Query

USE [Metrics] 
INSERT INTO dbo.tblSplitData(SplitKey, SplitString, SplitValues)
SELECT s.RawKey, s.SplitString, v.SplitValues
FROM (
SELECT d.RawKey, d.DelimitedString,
 c.item SplitString, c.rn
FROM dbo.tblRawData d
CROSS APPLY dbo.splitstring(d.DelimitedString, ',') c
) s

INNER JOIN

(
SELECT d.RawKey, d.DelimitedValues,
 c.item SplitValues, c.rn
FROM dbo.tblRawData d
CROSS APPLY dbo.splitstring(d.DelimitedValues, ',') c
) v
on s.RawKey = v.RawKey
and s.rn = v.rn;

Solution

  • It might be easier to answer this if we could see your split string function. My answer is using a version of my split function that I have.

    I would include in your split function a row number that you can use to JOIN the split string and the split values.

    Split function:

    CREATE FUNCTION [dbo].[Split](@String varchar(MAX), @Delimiter char(1))       
    returns @temptable TABLE (items varchar(MAX), rn int)       
    as       
    begin      
        declare @idx int       
        declare @slice varchar(8000)   
        declare @rn int = 1 -- row number that increments with each value in the delimited string
    
        select @idx = 1       
            if len(@String)<1 or @String is null  return       
    
        while @idx!= 0       
        begin       
            set @idx = charindex(@Delimiter,@String)       
            if @idx!=0       
                set @slice = left(@String,@idx - 1)   
            else       
                set @slice = @String       
    
            if(len(@slice)>0)  
                insert into @temptable(Items, rn) values(@slice, @rn)       
    
            set @String = right(@String,len(@String) - @idx)       
            set @rn = @rn +1
    
            if len(@String) = 0 break       
        end   
    return 
    end;
    

    Then if you have multiple columns to split, you could use a query similar to the following:

    INSERT INTO dbo.tblSplitData(SplitKey, SplitString, SplitValues)
    select s.rawkey,
      s.splitstring,
      v.splitvalues
    from
    (
      SELECT d.RawKey, d.delimitedstring, d.delimitedvalues, 
        c.items SplitString, 
        c.rn
      FROM dbo.tblRawData d
      CROSS APPLY dbo.Split(d.DelimitedString, ',') c
    ) s
    inner join
    (
      SELECT d.RawKey, d.delimitedstring, d.delimitedvalues, 
        c.items SplitValues, 
        c.rn
      FROM dbo.tblRawData d
      CROSS APPLY dbo.Split(d.DelimitedValues, ',') c
    ) v
      on s.rawkey = v.rawkey
      and s.delimitedstring = v.delimitedstring
      and s.rn = v.rn;
    

    See SQL Fiddle with Demo

    This uses two subqueries that generate the list of split values, then they are joined using the row number created by the split function.