Why can't I connect to the Database with symfony's propel ORM?

I'm building the blog project example 开发者_JAVA技巧shown in the "definitive guide of symfony" (chapter 8: the model) on official webpage. When i do operations that affects the database (like save();) in symfony, this message appears:

Unable to open PDO connection [wrapped: SQLSTATE[28000] [1045] Access denied for user 'root'@'localhost' (using password: NO)]

I tried to find errors in propel configuration files and nothing found. I just did what the guide says, nothing else. Maybe i need to create by command line the database or something like.

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You need to properly configure databases.yml with a valid user and password for your MySQL server. Right now it's trying to connect as the root user with no password, and it appears that's not valid for your local MySQL configuration.