If you know the values are from 1 to 100, then you can do this:
select n.num
from (select d1.d*10 + d2.d as n
from (select 0 as d union all select 1 union all select 2 union all select 3 union all select 4 union all
select 5 union all select 6 union all select 7 union all select 8 union all select 9
) d1 cross join
(select 0 as d union all select 1 union all select 2 union all select 3 union all select 4 union all
select 5 union all select 6 union all select 7 union all select 8 union all select 9
) d2
) nums left outer join
stands s
on s.stand = nums.n cross join
(select min(stand) as minstand and max(stand) as maxstand from stands) const
where s.stand is null and nums.n between minstand and maxstand;
This is not tested, so it may have syntax errors.
That is, create a table with all possible values (1 to 100). Left join this to your table. This gives you all the numbers that are not used. However, you want to limit it to the min and max values, so calcualte these and use them for filterin.