Split function equivalent in T-SQL?

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深忆病人
深忆病人 2020-11-21 07:23

I’m looking to split \'1,2,3,4,5,6,7,8,9,10,11,12,13,14,15...\' (comma delimited) into a table or table variable.

Does anyone have a function that returns each one

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  •  星月不相逢
    2020-11-21 08:08

    Using tally table here is one split string function(best possible approach) by Jeff Moden

    CREATE FUNCTION [dbo].[DelimitedSplit8K]
            (@pString VARCHAR(8000), @pDelimiter CHAR(1))
    RETURNS TABLE WITH SCHEMABINDING AS
     RETURN
    --===== "Inline" CTE Driven "Tally Table" produces values from 0 up to 10,000...
         -- enough to cover NVARCHAR(4000)
      WITH E1(N) AS (
                     SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL 
                     SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL 
                     SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1
                    ),                          --10E+1 or 10 rows
           E2(N) AS (SELECT 1 FROM E1 a, E1 b), --10E+2 or 100 rows
           E4(N) AS (SELECT 1 FROM E2 a, E2 b), --10E+4 or 10,000 rows max
     cteTally(N) AS (--==== This provides the "base" CTE and limits the number of rows right up front
                         -- for both a performance gain and prevention of accidental "overruns"
                     SELECT TOP (ISNULL(DATALENGTH(@pString),0)) ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
                    ),
    cteStart(N1) AS (--==== This returns N+1 (starting position of each "element" just once for each delimiter)
                     SELECT 1 UNION ALL
                     SELECT t.N+1 FROM cteTally t WHERE SUBSTRING(@pString,t.N,1) = @pDelimiter
                    ),
    cteLen(N1,L1) AS(--==== Return start and length (for use in substring)
                     SELECT s.N1,
                            ISNULL(NULLIF(CHARINDEX(@pDelimiter,@pString,s.N1),0)-s.N1,8000)
                       FROM cteStart s
                    )
    --===== Do the actual split. The ISNULL/NULLIF combo handles the length for the final element when no delimiter is found.
     SELECT ItemNumber = ROW_NUMBER() OVER(ORDER BY l.N1),
            Item       = SUBSTRING(@pString, l.N1, l.L1)
       FROM cteLen l
    ;
    

    Referred from Tally OH! An Improved SQL 8K “CSV Splitter” Function

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