【SQL】sql版Split函数。用于拆分字符串为单列表格

/*-------------------------------
函数：拆分字符串到单列表格v0.02
Author:AhDung
Update:201403251158
-------------------------------*/
ALTER FUNCTION dbo.Split(
@s VARCHAR(8000),             --要拆分的字符串
@separator NVARCHAR(10),      --分隔符。最长支持10个字符的分隔符
@removeEmpty BIT,             --是否移除空格项目。不处理制表符、回车换行
@unique BIT                   --是否移除重复项
)
RETURNS @t TABLE (S VARCHAR(500)) AS
BEGIN
  IF @s IS NULL RETURN
  
  IF CHARINDEX(@separator,@s)=0
  BEGIN INSERT @t VALUES(LEFT(@s,250)) RETURN END
  
  SET @s += @separator --仅对原串做一次改动。其实一次不改也行，但需要在循环中加判断。这样是为了在CPU和内存消耗之间取平衡
  DECLARE @lenS INT = LEN(@s),@lenSptr INT = DATALENGTH(@separator)/2,@i INT=0,@tmp NVARCHAR(250),@nextSptrIndex INT
  WHILE @i < @lenS
  BEGIN
    SET @nextSptrIndex=CHARINDEX(@separator,@s,@i+1)
    SET @tmp=SUBSTRING(@s,@i+1,@nextSptrIndex-1-@i)
    INSERT INTO @t VALUES(@tmp)
    SET @i+=DATALENGTH(@tmp)/2+@lenSptr
  END
  
  IF @removeEmpty=1
  BEGIN
  DELETE @t WHERE S=''
  END

  IF @unique=1
  BEGIN
  WITH cteA AS (SELECT ROW_NUMBER() OVER(PARTITION BY S ORDER BY S) AS 'ID' FROM @t)
  DELETE cteA WHERE ID<>1
  END

  RETURN
END