detecting foreign keys in a table (in any rdbms)

Database.FieldSchema has “IsPrimary”, but no “IsForeign”.

(ODBC provides the ability to query tables for foreign keys and the tables that they reference, but we are moving away from ODBC right now and transitioning to using rdbms-specific connectors.)

I’m hoping I just haven’t spotted it yet, but how can I query a table specifically for its foreign keys and the table(s) they reference?