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(dot)dickson(at)mail(dot)mcgill(dot)ca