Simon Rygård

Local Databases for Testing and Learning

Sometimes, you need a local database for testing/learning purposes. This post shows how to set up local databases of different types. The blog post will be updated as I learn more. The post assumes some familiarity with Docker and SQL but still has some in-depth explanations to make sure we understand the commands we’re running.

PostgreSQL

Docker

The following steps are based on the Docker blog post on how to use the PostgreSQL Docker official image.

Fist, run a PostgreSQL container:

docker run --name some-postgres -e POSTGRES_PASSWORD=mysecretpassword -d postgres

where:

• run - run a command in a new container
• name - name of the container
• e - environment variable
  • POSTGRES_PASSWORD - password for the (default) user postgres
• d - run the container in the background (detached mode)

Then, connect to the container:

docker exec -it some-postgres psql -U postgres

where:

• exec - execute a command in a running container
• it - interactive terminal
• some-postgres - name of the container
• psql - command to run
  • U - username
    • postgres - default username

When connected to the container, we can run SQL commands:

CREATE DATABASE mydb; -- create a database

\l -- list databases
\c mydb -- connect to a database

CREATE TABLE table (name VARCHAR(20), age INT); -- create a table

\dt -- list tables

INSERT INTO mydb (name, age) VALUES ('John', 30);

To disconnect from the database and container, simply press Ctrl/Cmd + D.

To stop the postgres container:

docker stop some-postgres

To start it up again, run:

docker start some-postgres

and then, again, the docker exec command from above.