1. disregarding "advanced" because thats subjective, you can think of a new type in a relational database as a table, where instances of that type are rows. 2.

1. disregarding "advanced" because thats subjective, you can think of a new type in a relational database as a table, where instances of that type are rows. 2. assuming by type reusability you mean something like polymorphism, sql affords subtype polymorphism through "disjoint subtyping" which means a single table which tracks multiple sub-tables, with a single entry existing in at most 1 of these sub-tables. sql also offers a limited row polymorphism through select and views. 3. assuming you're talking about all programming languages, yes. that doesn't mean instances of those types are shareable between languages. 4. yes. several interpreted languages have competing and optional type systems.