> How to Create auto_increment field in PostreSQL.
Its called the SERIAL datatype:
create table test_table (
field1 serial,
constraint test_table_pkey primary key (field1));
> Can I create them using Trigger.
Yes, alternatively, but I'm told that is not recommended because the
server source code that manages the special sequence table is highly
optimized for this specific functionality.
~Berend Tober