在SQL中过滤重复字符的函数

2008-7-14 11:02:14 喝小酒的网摘

在SQL中过滤重复字符的函数

共有三个函数，如下：
--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

--------------------------------------------------------------------
IF OBJECT_ID('DBO.SPLIT_STR') IS NOT NULL
DROP FUNCTION DBO.SPLIT_STR
GO
CREATE FUNCTION DBO.SPLIT_STR(
@S varchar(8000),      --包含多个数据项的字符串
@INDEX int,             --要获取的数据项的位置
@SPLIT varchar(10)     --数据分隔符
)
RETURNS VARCHAR(100)
AS
BEGIN
IF @S IS NULL RETURN(NULL)
DECLARE @SPLITLEN int
SELECT @SPLITLEN=LEN(@SPLIT+'A')-2
WHILE @INDEX>1 AND CHARINDEX(@SPLIT,@S+@SPLIT)>0
SELECT @INDEX=@INDEX-1,@S=STUFF(@S,1,CHARINDEX(@SPLIT,@S+@SPLIT)+@SPLITLEN,')
RETURN(ISNULL(LEFT(@S,CHARINDEX(@SPLIT,@S+@SPLIT)-1),'))
END
GO
PRINT DBO.SPLIT_STR('AA|BB|CC',2,'|')
--
GO
--结果
--呵呵
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