We can also use complex values in queries: anywhere in a query where a set
is expected, we can enumerate a set.
select name, date
where name in set (``salesplan'', ``opportunities'', ``risks'')
To create new objects, we can use constructor functions.
The constructor function for an object type T is T();
when it is invoked it creates a new uninitialized object of type T,
fills in its oid field, and returns the object.
The fields of the object must then be initialized.