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

select 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)