This document discusses using external tables in Oracle Database to load and query data from files. It describes using external tables for ad-hoc queries, ad-hoc loading, ongoing loading, and runtime adjustments. It provides examples of using external tables to load transit schedule data from a GTFS feed into relational tables with a procedure to periodically reload the data. Key aspects covered include defining external tables inline, using SQL*Loader Express Mode for ad-hoc loading, and overriding parameters in queries for runtime adjustments.