查看完整版本: SQL自定义函数--过滤重复字符

SQL自定义函数--过滤重复字符

IF OBJECT_ID('DBO.DISTINCT_STR') IS NOT NULL
DROP FUNCTION DBO.DISTINCT_STR
GO
CREATE FUNCTION DBO.DISTINCT_STR(@S NVARCHAR(100),@SPLIT VARCHAR(50))
RETURNS VARCHAR(100)
AS
BEGIN
IF @S IS NULL RETURN(NULL)
DECLARE @NEW VARCHAR(50),@INDEX INT,@TEMP VARCHAR(50)
IF LEFT(@S,1)<>@SPLIT
SET @S = @SPLIT+@S
IF RIGHT(@S,1)<>@SPLIT
SET @S = @S+@SPLIT
WHILE CHARINDEX(@SPLIT,@S)>0 AND LEN(@S)<>1
BEGIN
SET @INDEX = CHARINDEX(@SPLIT,@S)
SET @TEMP = LEFT(@S,CHARINDEX(@SPLIT,@S,@INDEX+LEN(@SPLIT)))
IF @NEW IS NULL
SET @NEW = ISNULL(@NEW,'')+@TEMP
ELSE
SET @NEW = ISNULL(@NEW,'')+REPLACE(@TEMP,@SPLIT,'')+@SPLIT
WHILE CHARINDEX(@TEMP,@S)>0
BEGIN
SET @S=STUFF(@S,CHARINDEX(@TEMP,@S)+LEN(@SPLIT),CHARINDEX(@SPLIT,@S,CHARINDEX(@TEMP,@S)+LEN(@SPLIT))-CHARINDEX(@TEMP,@S),'')
END
END
RETURN RIGHT(LEFT(@NEW,LEN(@NEW)-1),LEN(LEFT(@NEW,LEN(@NEW)-1))-1)
END
GO
PRINT DBO.DISTINCT_STR('A,A,B,C,C,B,C,',',')
--A,B,C
GO
--------------------------------------------------------------------
--过滤重复字符2
IF OBJECT_ID('DBO.DISTINCT_STR2') IS NOT NULL
DROP FUNCTION DBO.DISTINCT_STR2
GO
CREATE FUNCTION DBO.DISTINCT_STR2(@S varchar(8000))
RETURNS VARCHAR(100)
AS
BEGIN
IF @S IS NULL RETURN(NULL)
DECLARE @NEW VARCHAR(50),@INDEX INT,@TEMP VARCHAR(50)
WHILE LEN(@S)>0
BEGIN
SET @NEW=ISNULL(@NEW,'')+LEFT(@S,1)
SET @S=REPLACE(@S,LEFT(@S,1),'')
END
RETURN @NEW
END
GO
SELECT DBO.DISTINCT_STR2('AABCCD')
--ABCD
GO