query() method sends a SQL
query to the database. If the query is an insert statement, the return
value is the OID of the newly inserted row.
If it is otherwise a query that does not return a result
(i.e., is not a some kind of SELECT statement), it returns None.
Otherwise, it returns a pgqueryobject that can be accessed via the
getresult() or dictresult()
methods or simply printed.