SQL/function as default value in form

Dear All,

I currently using OO 2.0 m118 with postgresql driver version 0.6.2.

My question, is it posible to use a SQL or function that generate a value as a 
default value? please tell me the tricks.

the reason are, i use to use php as the front end of postgresql and using 
epoch in postgresql to generate id number instead of using auto 
increment/serial. I also found that the postgresql driver for OO still gives 
incosistency in updating serial field in subform.(sometime it updates, 
sometime it doesn't).

Thanks in advance,
Budi.