SQL Server Url Decode函数

CREATE FUNCTION dbo.UrlDecode(@url varchar(3072))
RETURNS varchar(3072)
AS
BEGIN 
    DECLARE @count int, @c char(1), @cenc char(2), @i int, @urlReturn varchar(3072) 
    SET @count = Len(@url) 
    SET @i = 1 
    SET @urlReturn = '' 
    WHILE (@i <= @count) 
     BEGIN 
        SET @c = substring(@url, @i, 1) 
        IF @c LIKE '[!%]' ESCAPE '!' 
         BEGIN 
            SET @cenc = substring(@url, @i + 1, 2) 
            SET @c = CHAR(CASE WHEN SUBSTRING(@cenc, 1, 1) LIKE '[0-9]' 
                                THEN CAST(SUBSTRING(@cenc, 1, 1) as int) 
                                ELSE CAST(ASCII(UPPER(SUBSTRING(@cenc, 1, 1)))-55 as int) 
                            END * 16 + 
                            CASE WHEN SUBSTRING(@cenc, 2, 1) LIKE '[0-9]' 
                                THEN CAST(SUBSTRING(@cenc, 2, 1) as int) 
                                ELSE CAST(ASCII(UPPER(SUBSTRING(@cenc, 2, 1)))-55 as int) 
                            END) 
            SET @urlReturn = @urlReturn + @c 
            SET @i = @i + 2 
         END 
        ELSE 
         BEGIN 
            SET @urlReturn = @urlReturn + @c 
         END 
        SET @i = @i +1 
     END 
    RETURN @urlReturn
END

CREATE FUNCTION dbo.fnDeURL
(
    @URL VARCHAR(8000)
)
RETURNS VARCHAR(8000)
AS
BEGIN
    DECLARE @Position INT,
        @Base CHAR(16),
        @High TINYINT,
        @Low TINYINT,
        @Pattern CHAR(21)

    SELECT  @Base = '0123456789abcdef',
        @Pattern = '%[%][0-9a-f][0-9a-f]%',
        @URL = REPLACE(@URL, '+', ' '),
        @Position = PATINDEX(@Pattern, @URL)

    WHILE @Position > 0
        SELECT  @High = CHARINDEX(SUBSTRING(@URL, @Position + 1, 1), @Base COLLATE Latin1_General_CI_AS),
            @Low = CHARINDEX(SUBSTRING(@URL, @Position + 2, 1), @Base COLLATE Latin1_General_CI_AS),
            @URL = STUFF(@URL, @Position, 3, CHAR(16 * @High + @Low - 17)),
            @Position = PATINDEX(@Pattern, @URL)

    RETURN  @URL
END