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

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  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. ;

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

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