SELECT help (fwd)

I am trying to do a select similar to the one below:

SELECT individual.first, individual.last, title_value.title
FROM individual, title_value, individual_staff_join_unit
WHERE individual.individual_id = 5307809
      AND
      individual_staff_join_unit.main_id = individual.main_id
      AND
      title_value.title_id = individual_staff_join_unit.title_id;

                  Table "individual"
 Attribute        |          Type          | Modifier
------------------+------------------------+----------
 individual_id    | integer                |
 main_id          | integer                |
 first            | character varying(40)  |
 last             | character varying(40)  |

    Table "individual_staff_join_unit"
 Attribute   |  Type   | Modifier
-------------+---------+----------
 main_id     | integer |
 unit_id     | integer |
 title_id    | integer |

               Table "title_value"
 Attribute |         Type          | Modifier
-----------+-----------------------+----------
 title_id  | integer               |
 title     | character varying(40) |

Every individual has a individual_id and a main_id.

The problem is that some rows in the individual_staff_join_unit table have
title_id = 0 and there is no row in title_value with title = 0. If this is
the case then no row is retrieved for the above SELECT.

Q: Is it possible to still get the individual.first and individual.last
from the table if the individual_staff_join_unit.title_id = 0 using only
one select statement and without modifying any of the tables, and to get
individual.first, individual.last and title_value.title if
individual_staff_join_unit.title_id != 0?

--
David A Dickson
david.dickson@mail.mcgill.ca