Is it possible to add just a column to a table? (oracle sql)

Question

I have this table:

  Person Name       Birthday        City   
      Mary          December       New York
      John           March          Seatle
      Peter         November       Los Angeles  

Assuming all people are male...

how can i add a new column Gender with value M, like the example below? Is it possible?

  Person Name       Birthday        City         Gender
      Mary          December       New York        M
      John           March          Seatle         M
      Peter         November       Los Angeles     M

Answer 1

Yes:

alter table t add gender varchar2(1) default 'M'

EDIT:

If you just want to return a column in a SELECT , you can do:

select t.*, 'M' as gender
from t;

However, you cannot modify the table from a SELECT .