After you download an open-source Rails project, do you have to db:migrate?

This is probably a stupidly easy question for a Rails person but is causing me no end of confusion. I downloaded several open source Rails projects but am not able to run them. Usually, are you supposed to do a db:migrate before you try to run a Rails project? I thought they were supposed to just run.

From stackoverflow

• I guess it depends on how the database is configured. If it's pointing to a sqlite db, then its probably all ready to go, otherwise if its a full blown RDBMS, then yes the database would need to be migrated assuming of course that the settings in database.yml are configured correctly.

  Chris Collins : Ok. Thanks .