A database is the top-level named collection of database objects. It contains schemas, which organize tables, views, functions, triggers, and other objects under logical names. section 2.1
Use separate databases to isolate datasets and application workloads. Tables in different schemas within one database can be queried together; tables in different databases cannot be joined directly through ordinary SQL. section 2.1
Connect to the default database
With a Postgres container running, execute `docker exec -it postgres psql -U postgres`. This connects to the default `postgres` database through the container’s local socket; use `\q` to exit. section 1.4
Listing 1.3 Connecting with psql
docker exec -it postgres psql -U postgres
Open the command listing for a runnable connection example. section 1.4
