标量值函数—— 判断是否存在特殊字符

Create    FUNCTION [dbo].[IsOnlyNumAndEngth] --只允许数字，字幕和一个额外的特殊字符
    (
      @str VARCHAR(8000),
      @escape1 CHAR = '' --额外的特殊字符
    )
RETURNS BIT
AS 
    BEGIN 
        DECLARE @i INT 
        DECLARE @j INT 
        DECLARE @k BIT 
        DECLARE @g CHAR
        SET @i = DATALENGTH(@str) 
        SET @j = 1 
        SET @k = 1 
        IF @str = '' 
            BEGIN
                SET @k = 0 
            END
        WHILE @j <= @i 
            BEGIN 
                SET @g = SUBSTRING(@str, @j, 1)
                IF ( ASCII(@g) NOT IN ( ASCII('1'), ASCII('2'), ASCII('3'),
                                        ASCII('4'), ASCII('5'), ASCII('6'),
                                        ASCII('7'), ASCII('8'), ASCII('9'),
                                        ASCII('0'), ASCII('Q'), ASCII('W'),
                                        ASCII('E'), ASCII('R'), ASCII('T'),
                                        ASCII('Y'), ASCII('U'), ASCII('I'),
                                        ASCII('O'), ASCII('P'), ASCII('A'),
                                        ASCII('S'), ASCII('D'), ASCII('F'),
                                        ASCII('G'), ASCII('H'), ASCII('J'),
                                        ASCII('K'), ASCII('L'), ASCII('Z'),
                                        ASCII('X'), ASCII('C'), ASCII('V'),
                                        ASCII('B'), ASCII('N'), ASCII('M'),
                                        ASCII('q'), ASCII('w'), ASCII('e'),
                                        ASCII('r'), ASCII('t'), ASCII('y'),
                                        ASCII('u'), ASCII('i'), ASCII('o'),
                                        ASCII('p'), ASCII('a'), ASCII('s'),
                                        ASCII('d'), ASCII('f'), ASCII('g'),
                                        ASCII('h'), ASCII('j'), ASCII('k'),
                                        ASCII('l'), ASCII('z'), ASCII('x'),
                                        ASCII('c'), ASCII('v'), ASCII('b'),
                                        ASCII('n'), ASCII('m'),
                                        ASCII(@escape1) ) ) 
                    BEGIN 
                        SET @k = 0 
                        BREAK 
                    END
                SET @j = @j + 1 
            END 
        RETURN   @k 
    END