-- 功能: 将二进制字符串(VARCHAR)转换为十进制数(INT)
-- 输入参数: @StrBin 待转换的二进制字符串
-- 返回值: 相应的十进制数,如果二进制数非法,返回-1
-- 注意: @StrBin的长度不能大于31
-- 作者: cheyo@JMU           Email:  cheyocn at hotmail.com
-- 来源: telnet://bbs.jmu.edu.cn   http://bbs.jmu.edu.cn
-- 日期: 2005-10-05
-- 例子: SELECT dbo.Bin2Dec(‘1001‘) AS ‘15的二进制表示‘
CREATE FUNCTION Bin2Dec(@StrBin VARCHAR(31))
RETURNS BIGINT                        ---- 只支持最多31位长二进制字符串的解析
AS
BEGIN
    DECLARE @DecValue AS BIGINT       -- 十进制值
    DECLARE @BinLen AS TINYINT     -- 二进制字符串长度
    DECLARE @Index AS TINYINT      -- 处理二进制字符串长度的索引
    DECLARE @CurrBit AS CHAR(1)    -- 当前在处理哪一位
    SET @BinLen = LEN(@StrBin)
    SET @DecValue = 0
    SET @Index = 0
    WHILE @Index < @BinLen
    BEGIN
        SET @Index = @Index + 1
        SET @CurrBit = CAST(SUBSTRING(@StrBin, @Index, 1) AS CHAR(1))
            IF (@CurrBit <> ‘0‘ AND @CurrBit <> ‘1‘)   -- 出现非法字符,返回-1   
            BEGIN
                SET @DecValue = -1
                BREAK
            END
        ELSE     
            BEGIN
                SET @DecValue = @DecValue * 2
                IF(@CurrBit = ‘1‘)
                    BEGIN
                        SET @DecValue = @DecValue + POWER(2, 0)
                    END
            END      
    END
    
    RETURN @DecValue
END
GO