SqlServer字符串替换并去重

/*
  功能说明：字符串替换并去重, 字符串每一项以 @delimiter 隔开
  参数说明：@job_type_list 待处理字符串;   @delimiter 分割符号, @oldtype 待替换字符串,   @newtype 替换的字符串
  输出结果说明：
	Set @delimiter =','
	SET @job_type_list = '123,45'	
	SET @newtype='13'
	SET @oldtype='45'
	Return "123,13"
	SET @job_type_list = '123,45,13,2,45'
	SET @newtype='13'
	SET @oldtype='45'
	Return "123,13,2"
*/


CREATE      FUNCTION [zhaopin].[FN_ReplaceString]
(     
   @job_type_list varchar(1000),
   @delimiter char(1),
   @oldtype varchar(100),
   @newtype varchar(100) 
)
RETURNS varchar(1000)
As
begin
	declare @jobtype varchar(1000)
	declare @number int
	DECLARE @startpos int
	if (@job_type_list is NULL)
		return null
	
	if  (@oldtype is null or @newtype is NULL)
		return @job_type_list

	SET @job_type_list = replace(@job_type_list, ' ', '')
	SET @jobtype = replace(@delimiter + @job_type_list + @delimiter , @delimiter + @oldtype + @delimiter, @delimiter + @newtype + @delimiter)

	SET @number = len(replace(@jobtype,@newtype,@newtype+'-'))-len(@jobtype)
	IF @number>1 
	BEGIN
		SET @startpos = CHARINDEX(@delimiter + @newtype + @delimiter,@jobtype) + LEN(@delimiter + @newtype + @delimiter)
		SET @job_type_list = left(@jobtype,@startpos-1)		
		SET @jobtype = SUBSTRING(@jobtype, @startpos-1,LEN(@jobtype))
		WHILE(CHARINDEX(@delimiter + @newtype + @delimiter,@jobtype)>0)
		BEGIN
			SET @jobtype = replace(@jobtype,@delimiter + @newtype + @delimiter,',')
		END	
		IF(LEFT(@jobtype, 1) = @delimiter )
			SET @jobtype=RIGHT(@jobtype,LEN(@jobtype)-1)
		SET @jobtype = @job_type_list + @jobtype
	END

	IF(len(@jobtype)>2)
		SET @jobtype = substring(@jobtype,2,len(@jobtype)-2)

	RETURN @jobtype
end