It is possible to build databases for both PostgreSQL and MySQL with
```bash
$ cd activerecord
$ bundle exec rake db:create
```
You can cleanup the databases using
```bash
$ cd activerecord
$ bundle exec rake db:drop
```
NOTE: Using the rake task to create the test databases ensures they have the correct character set and collation.
NOTE: You'll see the following warning (or localized warning) during activating HStore extension in PostgreSQL 9.1.x or earlier: "WARNING: => is deprecated as an operator".