Rails and Databases

The examples in this course were written using SQLite 3 (version 3.22.0 or thereabouts). If you want to follow along with our code, it’s probably simplest if you use SQLite 3 as well. If you decide to use something else, it won’t be a major problem. You may have to make minor adjustments to any explicit SQL in our code, but Rails pretty much eliminates database-specific SQL from applications.

Connection with database

If you want to connect to a database other than SQLite 3, Rails also works with DB2, MySQL, Oracle Database, Postgres, Firebird, and SQL Server. For all but SQLite 3, you’ll need to install a database driver—a library that Rails can use to connect to and use with your database engine. This section contains links to instructions to do that.

The database drivers are all written in C and are primarily distributed in source form. If you don’t want to bother building a driver from the source, take a careful look at the driver’s website. Many times, you’ll find that the author also distributes binary versions.

If you can’t find a binary version or if you’d rather build from source anyway, you need a development environment on your machine to build the library. For Windows, you need a copy of Visual C++. For Linux, you need gcc and friends, but these will likely already be installed.

On OS X, you need to install the developer tools. They come with the operating system but aren’t installed by default. You also need to install your database driver into the correct version of Ruby. If you installed your own copy of Ruby, bypassing the built-in one. It’s important to have this version of Ruby first in your path when building and installing the database driver. You can use the which ruby command to make sure you’re not running Ruby from /usr/bin.

The following are the available database adapters and the links to their respective home pages: