--建测试表
create table fy
(id int not null,
 bcol binary(5) not null
 constraint pk_fy primary key(id)
)

insert into fy
select 1,convert(binary(5),getdate()) union all
select 2,convert(binary(5),4)

select id,bcol from fy

id          bcol
----------- ------------
1           0x26009DAD1F
2           0x0000000004

--问题重现
select id,cast(bcol as varchar) bcol from fy

id          bcol
----------- ------------------------------
1           & 澀
2               

select id,convert(varchar,bcol) bcol from fy

id          bcol
----------- ------------------------------
1           & 澀
2               


--解决方法
--1.建函数ConvertVarBinary_HexStr
create function dbo.ConvertVarBinary_HexStr
( @bin varbinary(1000))
returns varchar(1000)
as
begin
    DECLARE @Return varchar(1000), @ind int, @byte binary(1),@byte1 int, @byte2 int;
    SELECT @Return = '',@ind = 1;
    
    WHILE ( @ind <= datalength(@bin) )
    BEGIN
        SELECT @byte = substring(@bin, @ind, 1);
        SET @byte1 = @byte / 16
        IF(@byte1 >= 10)
            SELECT @Return = @Return + 
                CASE @byte1
                    WHEN 10 THEN 'A'
                    WHEN 11 THEN 'B'
                    WHEN 12 THEN 'C'
                    WHEN 13 THEN 'D'
                    WHEN 14 THEN 'E'
                    WHEN 15 THEN 'F'
                END
        ELSE
            SELECT @Return = @Return + convert(char(1),@byte1)

        SET @byte2 = @byte % 16
        IF(@byte2 >= 10)
            SELECT @Return = @Return + 
                CASE @byte2
                    WHEN 10 THEN 'A'
                    WHEN 11 THEN 'B'
                    WHEN 12 THEN 'C'
                    WHEN 13 THEN 'D'
                    WHEN 14 THEN 'E'
                    WHEN 15 THEN 'F'
                END
        ELSE
            SELECT @Return = @Return + convert(char(1),@byte2)

        SELECT @ind = @ind + 1;
    END

    RETURN @Return;
end

--2.使用函数ConvertVarBinary_HexStr转换binary列值
select id,dbo.ConvertVarBinary_HexStr(bcol) 'bcol' from fy

--结果(已是varchar类型).
id          bcol
----------- ------------
1           26009DAD1F
2           0000000004

(2 row(s) affected)

------解决方案--------------------
修改

选项/查询结果    最大字符看看