From the docks :
priv_level: { * | *.* | db_name.* | db_name.tbl_name | tbl_name | db_name.routine_name }
Privilege Levels
For each database, it can be set up. Certain privileges can only be set at certain levels.
Global privileges are granted using *.* For priv_level. Global privileges include privileges for all tables, functions, and procedures. Global privileges are stored in the mysql.user table.
Database privileges are granted using db_name.* For priv_level, or using the default database. Database privileges include tables and functions, as well as privileges for all tables, functions, and procedures in the database. Database privileges are stored in the mysql.db table. Table privileges are granted for the priv_level, or you can specify a table in the default database. The TABLE keyword is optional.
Table privileges in the table. Certain table privileges for individual columns.
Column privileges are granted by the list column after the privilege type. You can select and change.
Function privileges are granted using the program to specify a function.
Procedure privileges are granted by the db_name.routine_name for priv_level, or using the protocol.
Namely that is . , and what is db_name. *?
*.* - all objects in all databases (in this instance)
How to create a mysql user with the rights to only one database?
grant usage on db_name.* to your_user@localhost identified by 'your_user_password';
or if you need to give all rights in one database:
grant all privileges on db_name.* to your_user@localhost identified by 'user_password';