if exists ...

Hi,

writing Postgres SQL scripts I have the problem: how do I check if a
database object already exists?

Having a list of create table, create trigger, create view ...
statements I have to decide if the script first drops the existing old
object or if it doesn't already exist to create it without dropping.

Transact-Sql allows the following construct:
if exists (select * from sysobjects where id = object_id(...) = 1)
drop trigger tCompUTrig
GO

I know that postgres has the "table_exists" function. But I don't know
the syntax to integrate it in a script with create and drop statements.

Any ideas?

Greetings,
Andreas