SQL 二进制和字符互转

1.二进制转为字符串

ALTER function varbin2hexstr(
    @bin varbinary(8000)
)returns varchar(8000)
as
begin
    declare @re varchar(8000),@i int
    select @re='',@i=datalength(@bin)
    while @i>0
        select @re=substring('0123456789ABCDEF',substring(@bin,@i,1)/16+1,1)
                +substring('0123456789ABCDEF',substring(@bin,@i,1)%16+1,1)
                +@re
            ,@i=@i-1
    -- return('0x'+@re)
    return @re
end

2.字符串转为二进制

CREATE function [dbo].[hexstr2varbin](
  @char varchar(8000)
)returns varbinary(8000)
as
begin
    declare @re varbinary(8000), @tempchar varchar(2),
            @getchar varchar(1), @getint int, @n int, @totalint int,
            @i int, @tempint int, @runNum int -- 字符串截取段数

     select @tempchar='',@i=datalength(@char), @re=0x; 

    if( @i>0)
    begin
        if ( @i%2 = 0) set @runNum= @i/2
        else set @runNum= @i/2 + 1 

        while (@runNum > 0)
        begin
            if(@runNum = 1) set @tempchar = @char
            else set @tempchar = substring(@char, (@runNum)*2-1,2) --截取字符长度

            select @n=1,@totalint=0;

            -- 循环处理截取的每个字符串 (这里的字符串长度为2)
            while @n < ( datalength(@tempchar) + 1 )
            begin
                set @getchar=substring(@tempchar,@n,1);

                -- 将字符转换为十六进制对应的数字
                select @getint=case
                       when @getchar='a' then 10
                       when @getchar='b' then 11
                       when @getchar='c' then 12
                       when @getchar='d' then 13
                       when @getchar='e' then 14
                       when @getchar='f' then 15
                       else  convert(int,@getchar) end;

                set @tempint=@getint*power(16,datalength(@tempchar)-@n)
                set @totalint = @totalint + @tempint
                set @n=@n+1
            end 

               set @re=convert(varbinary(1),@totalint) + @re;
               set @runNum=@runNum-1;
        end
    end
   return @re

end
GO