Configuring a Database
Just about every Rails application will interact with a database. The database to use is specified in a configuration file, config/database.yml. If you open this file in a new Rails application, you’ll see a default database configured to use SQLite3. The file contains sections for three different environments in which Rails can run by default:
- The development environment is used on your development/local computer as you interact manually with the application.
- The test environment is used when running automated tests.
- The production environment is used when you deploy your application for the world to use.
1) Configuring an SQLite3 Database
Rails comes with built-in support for SQLite3, which is a lightweight serverless database application. While a busy production environment may overload SQLite, it works well for development and testing. Rails defaults to using an SQLite database when creating a new project, but you can always change it later.
Here’s the section of the default configuration file (config/database.yml) with connection information for the development environment:
In this guide we are using an SQLite3 database for data storage, because it is a zero configuration database that just works. Rails also supports MySQL and PostgreSQL “out of the box”, and has plugins for many database systems. If you are using a database in a production environment Rails most likely has an adapter for it.
2) Configuring a MySQL Database
If you choose to use MySQL instead of the shipped SQLite3 database, yourconfig/database.yml will look a little different. Here’s the development section:
If your development computer’s MySQL installation includes a root user with an empty password, this configuration should work for you. Otherwise, change the username and password in the development section as appropriate and you can also do these changes in test and production sections too.
3) Configuring a PostgreSQL Database
If you choose to use PostgreSQL, your config/database.yml will be customized to use PostgreSQL databases:
You can also do these changes in test and production sections.
Change the username and password in the development section as appropriate.
Creating the Database
Now that you have your database configured, it’s time to have Rails create an empty database for you. You can do this by running a rake command:
This will create your development and test databases inside the db/ folder