Follow this step-by-step guide to install PostgreSQL, load data, connect to a database, and execute SQL queries including table joins PostgreSQL is an open-source, object-relational (also called ...

Read this SQL tutorial to learn when to use SELECT, JOIN, subselects and UNION to access multiple tables with a single statement.

Want faster SQL queries? Here are nine best practices for writing SQL queries that work like a charm (or at least, like they should).

Query federation is a way to make use of distributed data sources on the Web, including many SPARQL endpoints as well as relational databases. SWObjects makes use of mapping rules represented as ...