Solution 2: Object-Relational
Idea: Add OO features to the type system of SQL. I.e. “plain old SQL”, but...
- columns can be of new types (ADTs)
- user-defined methods on ADTs
- columns can be of complex types
- reference types and “deref”
- inheritance
- old SQL schemas still work! (backwards compatibility)
Many relational vendors moving this way (SQL3). Big business!