While we won’t assume you’re a relational database expert, we do assume you have confronted a database or two in the past. Odds are good that the database was relational. We’ll start with creating our own schemas and populating them. Then we’ll take a look at querying for values and finally what makes relational databases so special: the table join.
Like most databases we’ll read about, Postgres provides a back-end server that does all of the work and a command-line shell to connect to the running server. The server communicates through port 5432 by default, which you can connect to with the psql shell.
$ psql book
PostgreSQL prompts with the name of the database followed by a hash mark if you run as ...