UNION with more restrictive DISTINCT

I'd like to UNION two queries but the distinct-criteria for UNION should
not be all columns in the queries, but only one.

example. two tables:

test=# select id,name from t1;
  id | name
----+------
   1 | bob
   2 | mike
(2 rows)

test=# select id,name from t2;
  id |  name
----+---------
   1 | bob
   2 | mike j.
(2 rows)


# select id,name from t1 union select id,name from t2;
  id |  name
----+---------
   1 | bob
   2 | mike
   2 | mike j.
(3 rows)


now I want a construct that returns me only one row for each id. If
there are different names for that id's in the different tables, the
name of t2 should be chosen.

like:

# select id,name from t1 UNION ON (id) AND SUPERMAGICPREFER (t2.name)
select id,name from t2;
  id |  name
----+---------
   1 | bob
   2 | mike j.
(2 rows)


What is an appropriate approach to this? If I use my UNION-query as
subquery for a SELECT DISTINCT ID, I loose the name, which is important.

thnx.
peter



--
mag. peter pilsl
goldfisch.at
IT-management
tel +43 699 1 3574035
fax +43 699 4 3574035
pilsl@goldfisch.at