sql删除左右字符之trim()函数用法

/******
Object: UserDefinedFunction [dbo].[TRIM]
Script Date: 11/18/2011 09:10:14
Author: EF
******/
IF EXISTS (SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[trim]') AND type in (N'FN', N'IF', N'TF', N'FS', N'FT'))
DROP FUNCTION [dbo].[trim]
GO
CREATE FUNCTION dbo.trim
(
@Source VARCHAR(MAX),
@Char CHAR(1)
)
RETURNS VARCHAR(MAX)
AS
BEGIN
DECLARE @i int;
DECLARE @returnString VARCHAR(MAX)
SET @returnString = @Source
--清除前后空格
SET @returnString = LTRIM(RTRIM(@returnString))
--删除左侧字符
SET @i = 0
WHILE @i=0
BEGIN
IF LEFT(@returnString,1) = @Char
SET @returnString = RIGHT(@returnString,LEN(@returnString)-1)
ELSE
SET @i=1
END
--删除右侧字符
SET @i = 0
WHILE @i=0
BEGIN
IF RIGHT(@returnString,1) = @Char
SET @returnString = LEFT(@returnString,LEN(@returnString)-1)
ELSE
SET @i=1
END
--清除前后空格
SET @returnString = LTRIM(RTRIM(@returnString))
RETURN @returnString;
END

GO

--测试

dbo.trim('asdfas;asdfasdfa;',';')
union all select dbo.trim(';asdfas;asdfasdfa;',';')
union all select dbo.trim(' ;asdfas;asdfasdfa;',';')
union all select dbo.trim('; asdfas;asdfasdfa;',';')

--结果

-------------------------------------------------------------------------

asdfas;asdfasdfa
asdfas;asdfasdfa
asdfas;asdfasdfa
asdfas;asdfasdfa

(4 行受影响)