Question

我在SQL Server的varchar（max）列中有值0x4D79205465737420537472696E67。我想将其转换为二进制值0x4D79205465737420537472696E67并检索第0个字节的前3位。

任何帮助都将不胜感激，谢谢。

Answer 1

DECLARE @x varchar(max) = '0x4D79205465737420537472696E67'
SELECT CONVERT(binary(1), LEFT(@x,4), 1) / 32

Answer 2

看看这是否适合您：

IF NOT EXISTS ( SELECT  1
                FROM    sys.objects
                WHERE   name = 'NthBit' 
                    AND type = 'FN' )
BEGIN
    --DROP FUNCTION dbo.NthBit;
    EXEC( 'CREATE FUNCTION dbo.NthBit() RETURNS INTEGER AS BEGIN RETURN 1; END' );
END;
GO

ALTER FUNCTION dbo.NthBit
(
    @StringRep          VARCHAR( MAX ),
    @ByteNumber         INTEGER = 0,
    @BitNumber          INTEGER = 0
) RETURNS BIT AS BEGIN
    /*
        Returns the nth bit of the binary representation of @StringRep,
            enumerated naively ( 01234567 rather than 76543210 )
     */
    RETURN  POWER( 2, 7 - @BitNumber ) 
                & ( SUBSTRING( CONVERT( VARBINARY( MAX ), @StringRep, 1 ), @ByteNumber + 1, 1 ) );
END;
GO

DECLARE @Binary     VARCHAR( MAX );
    SET @Binary = '0x4D79205465737420537472696E67';

SELECT  [1st] = dbo.NthBit( @Binary, 0, 0 ), -- Sign bit, in this case
        [2nd] = dbo.NthBit( @Binary, 0, 1 ), 
        [3rd] = dbo.NthBit( @Binary, 0, 2 ),
        [4th] = dbo.NthBit( @Binary, 0, 3 ), 
        [5th] = dbo.NthBit( @Binary, 0, 4 ), 
        [6th] = dbo.NthBit( @Binary, 0, 5 ),
        [7th] = dbo.NthBit( @Binary, 0, 6 ), 
        [8th] = dbo.NthBit( @Binary, 0, 7 );
GO

将varchar（MAX）数据转换为二进制格式并从第n个字节检索第n位

2 个答案: