I'm adding a table and subclass table to my DB. (Subclass table = table where the primary key joins to the primary key of another table, to give extra row information to some subset of the rows.

Modern relational database features in PostgreSQL include complex queries, foreign keys, triggers, updatable views, transactional integrity, and multi-version concurrency control.

The ease and ubiquity of SQL have even led the creators of many “ NoSQL ” or non-relational data stores, such as Hadoop, to adopt subsets of SQL or come up with their own SQL-like query languages.