insert into tb select col from ( select 1 col union select 2 union select 3 union select 4 union select 5 union select 6 union select 7 union select 8 union select 9 union select 10 union select 11 union select 12 union select 13 union select 14) t where not exists(select * from tb where num=t.col)
select col
from (
select 1 col union select 2 union
select 3 union select 4 union
select 5 union select 6 union
select 7 union select 8 union
select 9 union select 10 union
select 11 union select 12 union
select 13 union select 14) t
where not exists(select * from tb where num=t.col)