Examples in this section can also be found in advance.sql in the tutorial directory. Inheritance Let's create two classes. The capitals class contains state capitals which are also cities. Naturally, the capitals class should inherit from cities.
State capitals have an extra attribute, state, that shows their state.
This feature allows a user to run historical queries. One can also give a time range. One of the tenets of the relational model is that the attributes of a relation are atomic. For example, you can create attributes that are arrays of base types. Arrays of any base type or user-defined type can be created.