Split a String with Specific Separator Character

Introduction

Write a table function to split a string with specific separator character.

Example:

SELECT * FROM dbo.Split('john, peter, mary', ',')

And result:

• john
• peter
• mary

CREATE FUNCTION [dbo].[Split](@array NVARCHAR(MAX),@separator char(1))
RETURNS @tbl TABLE (string nvarchar(128) NOT NULL) AS
BEGIN
      DECLARE @pos      int,
              @textpos  int,
              @chunklen smallint,
              @str      nvarchar(MAX),
              @tmpstr   nvarchar(MAX),
              @leftover nvarchar(MAX)

      SET @textpos = 1
      SET @leftover = ''
      WHILE @textpos <= datalength(@array) / 2
      BEGIN
         SET @chunklen = 4000 - datalength(@leftover) / 2
         SET @tmpstr = ltrim(@leftover + substring(@array, @textpos, @chunklen))
         SET @textpos = @textpos + @chunklen

         SET @pos = charindex(@separator, @tmpstr)
         WHILE @pos > 0
         BEGIN
            SET @str = substring(@tmpstr, 1, @pos - 1)
            INSERT @tbl (string) VALUES(convert(nvarchar(20), @str))
            SET @tmpstr = ltrim(substring(@tmpstr, @pos + 1, len(@tmpstr)))
            SET @pos = charindex(@separator, @tmpstr)
         END

         SET @leftover = @tmpstr
      END

      IF ltrim(rtrim(@leftover)) <> ''
         INSERT @tbl (string) VALUES(convert(nvarchar(Max), @leftover))

      RETURN
   END
GO