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sql-servert-sqldatabase-cursor

Create a table from CSV columns in SQL Server without using a cursor


Given a table:

|Name    | Hobbies                |
-----------------------------------
|Joe     | Eating,Running,Golf    |
|Dafydd  | Swimming,Coding,Gaming |

I would like to split these rows out to get:

|Name    | Hobby     |
----------------------
|Joe     | Eating    |
|Joe     | Running   |
|Joe     | Golf      |
|Dafydd  | Swimming  |
|Dafydd  | Coding    |
|Dafydd  | Gaming    |

I have completed this below (example is ready to run in SSMS), buy my solution uses a cursor which I think is ugly. Is there a better way of doing this? I am on SQL Server 2008 R2 if there is anything new which will help me.

Thanks

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[Split]') and xtype in (N'FN', N'IF', N'TF')) drop function [dbo].Split
go
CREATE FUNCTION dbo.Split (@sep char(1), @s varchar(512))
RETURNS table
AS
RETURN (
    WITH Pieces(pn, start, stop) AS (
      SELECT 1, 1, CHARINDEX(@sep, @s)
      UNION ALL
      SELECT pn + 1, stop + 1, CHARINDEX(@sep, @s, stop + 1)
      FROM Pieces
      WHERE stop > 0
    )
    SELECT pn,
      SUBSTRING(@s, start, CASE WHEN stop > 0 THEN stop-start ELSE 512 END) AS s
    FROM Pieces
  )


go

declare @inputtable table (
    name varchar(200) not null,
    hobbies varchar(200) not null
)

declare @outputtable table (
    name varchar(200) not null,
    hobby varchar(200) not null
)

insert into @inputtable values('Joe', 'Eating,Running,Golf')
insert into @inputtable values('Dafydd', 'Swimming,Coding,Gaming')

select * from @inputtable

declare inputcursor cursor for
select name, hobbies
from @inputtable

open inputcursor

declare @name varchar(255), @hobbiescsv varchar(255)
fetch next from inputcursor into @name, @hobbiescsv
while(@@FETCH_STATUS <> -1) begin

    insert into @outputtable
    select @name, splithobbies.s
    from dbo.split(',', @hobbiescsv) splithobbies

    fetch next from inputcursor into @name, @hobbiescsv 
end
close inputcursor
deallocate inputcursor

select * from @outputtable

Solution

  • Use a string parsing function like the one found here. The key is to use CROSS APPLY to execute the function for each row in your base table.

    CREATE FUNCTION [dbo].[fnParseStringTSQL] (@string NVARCHAR(MAX),@separator NCHAR(1))
    RETURNS @parsedString TABLE (string NVARCHAR(MAX))
    AS 
    BEGIN
       DECLARE @position int
       SET @position = 1
       SET @string = @string + @separator
       WHILE charindex(@separator,@string,@position) <> 0
          BEGIN
             INSERT into @parsedString
             SELECT substring(@string, @position, charindex(@separator,@string,@position) - @position)
             SET @position = charindex(@separator,@string,@position) + 1
          END
         RETURN
    END
    go
    
    declare @MyTable table (
        Name char(10),
        Hobbies varchar(100)
    )
    
    insert into @MyTable
        (Name, Hobbies)
        select 'Joe', 'Eating,Running,Golf'
        union all
        select 'Dafydd', 'Swimming,Coding,Gaming'
    
    select t.Name, p.String
        from @mytable t
            cross apply dbo.fnParseStringTSQL(t.Hobbies, ',') p
    
    DROP FUNCTION [dbo].[fnParseStringTSQL]