在MySQL中将二进制字符串转换为bigint？

I am attempting to hash a string to a 64-bit value (bigint) in MySQL. I am aware of the MD5() function, which returns a 128-bit hash as a binary string. I'd be happy to just take the bottom or top 64 bits of this result. However, I cannot figure out how to get from a binary string type to a numeric type of any sort. Any pointers?

我试图在MySQL中将字符串哈希到64位值(bigint)。我知道MD5()函数,它返回一个128位散列作为二进制字符串。我很乐意把这个结果的底部或前64位。但是,我无法弄清楚如何从二进制字符串类型到任何类型的数字类型。有什么指针吗?

2 个解决方案

#1

Use the CONV() function to convert the MD5 hash from base 16 to base 10 and CAST to convert it to a number:

使用CONV()函数将MD5哈希从基数16转换为基数10和CAST将其转换为数字:

select cast(conv(substring(md5(id), 1, 16), 16, 10) as unsigned integer) from SomeTable;

#2

CREATE FUNCTION dbo.HexStrToVarBinary(@hexstr varchar(8000))
RETURNS varbinary(8000)
AS
BEGIN 
    DECLARE @hex char(1), @i int, @place bigint, @a bigint
    SET @i = LEN(@hexstr) 

    set @place = convert(bigint,1)
    SET @a = convert(bigint, 0)

    WHILE (@i > 0 AND (substring(@hexstr, @i, 1) like '[0-9A-Fa-f]')) 
     BEGIN 
        SET @hex = SUBSTRING(@hexstr, @i, 1) 
        SET @a = @a + 
    convert(bigint, CASE WHEN @hex LIKE '[0-9]' 
         THEN CAST(@hex as int) 
         ELSE CAST(ASCII(UPPER(@hex))-55 as int) end * @place)
    set @place = @place * convert(bigint,16)
        SET @i = @i - 1

     END 

    RETURN convert(varbinary(8000),@a)
END
GO 

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