Can you do a foreign key within a single table, though? I've only ever seen foreign key constraints tying a field in one table to a field in another table.

Which makes for a better primary key: natural data points or meaningless values? Database developers have strong opinions on this facet of primary key design. This article settles the debate once ...

Every JPA entity has a primary key, but some entities have more than one value as their primary key. In this case, you need to use a composite key. This Java tip introduces you to using composite ...