Error selecting database after connecting to database

When you write a PHP program, you successfully connect to the database. Selecting a database will show "error message: Access denied for user" @ ' localhost ' to database ' * * * * * * * And you go into the background database and see that the database is there. So why is the connection failing?

Baidu error message and observe the user after the existence of 3 localhost, then we connect to the database will choose Which?

That's what it's about. The default is to select the first one that any user can use for localhost. But it does not have permission, so we need to give him access to the database is OK.

Error selecting database after connecting to database