[Zope] [SQL] Retrieving info from the previous SQL insert

I have a SQL method which performs an INSERT in one table, followed by an INSERT into another table. The two INSERTs have to be in the same method because they need to be atomic. In the first table, there is an auto-incrementing field that the PostgreSQL DBMS assigns itself. I need the value of that field for the second INSERT and I don't see how to retrieve it inside the SQL method. Yes, I'll read more deeply PostgreSQL documentation and Zope documentation and <dtml-var my_postgresql_zope_adapter> documentation but, in the mean time, if someone has a ready-to-use solution?