Re: is there a select for update insert if not exist type command?

Depending on the version of Pg there are two possible solutions to
this problem.  The first (old solution) that really only works well
one row at a time is to do a stored procedure that does something
like:

update foo set bar = baz where id = in_id

if not found
   insert into foo (bar) values (baz)
end if;

The newer way, which can be done in SQL with Pg 9.1 is to use writable
common table expressions.  See
http://vibhorkumar.wordpress.com/2011/10/26/upsertmerge-using-writable-cte-in-postgresql-9-1/
for an example by Vibhor Kumar.

Best Wishes,
Chris Travers