Posted By

ezerick on 06/21/11


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Function to split a list into a table in T-SQL


 / Published in: SQL
 

URL: http://www.sqlservercentral.com/articles/Tally+Table/72993/

  1. CREATE FUNCTION dbo.DelimitedSplit8K
  2. --===== Define I/O parameters
  3. (@pString VARCHAR(8000), @pDelimiter CHAR(1))
  4. RETURNS TABLE WITH SCHEMABINDING AS
  5. RETURN
  6. --===== "Inline" CTE Driven "Tally Table" produces values from 0 up to 10,000...
  7. -- enough to cover VARCHAR(8000)
  8. WITH E1(N) AS (
  9. SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
  10. SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
  11. SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1
  12. ), --10E+1 or 10 rows
  13. E2(N) AS (SELECT 1 FROM E1 a, E1 b), --10E+2 or 100 rows
  14. E4(N) AS (SELECT 1 FROM E2 a, E2 b), --10E+4 or 10,000 rows max
  15. cteTally(N) AS (--==== This provides the "zero base" and limits the number of rows right up front
  16. -- for both a performance gain and prevention of accidental "overruns"
  17. SELECT 0 UNION ALL
  18. SELECT TOP (DATALENGTH(ISNULL(@pString,1))) ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
  19. ),
  20. cteStart(N1) AS (--==== This returns N+1 (starting position of each "element" just once for each delimiter)
  21. SELECT t.N+1
  22. FROM cteTally t
  23. WHERE (SUBSTRING(@pString,t.N,1) = @pDelimiter OR t.N = 0)
  24. )
  25. --===== Do the actual split. The ISNULL/NULLIF combo handles the length for the final element when no delimiter is found.
  26. SELECT ItemNumber = ROW_NUMBER() OVER(ORDER BY s.N1),
  27. Item = SUBSTRING(@pString,s.N1,ISNULL(NULLIF(CHARINDEX(@pDelimiter,@pString,s.N1),0)-s.N1,8000))
  28. FROM cteStart s
  29. ;

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