CREATE DATABASE `mydb`;

CREATE OR REPLACE USER 'myuser'@'localhost' IDENTIFIED BY 'password';

GRANT USAGE ON *.* TO 'myuser'@localhost;
GRANT ALL privileges ON `mydb`.* TO 'myuser'@localhost;
FLUSH PRIVILEGES;

SHOW GRANTS FOR 'myuser'@localhost;     
+--------------------------------------------------------------+ 
| Grants for myuser@localhost                                  | 
+--------------------------------------------------------------+ 
| GRANT USAGE ON *.* TO 'myuser'@'localhost'                   | 
| GRANT ALL PRIVILEGES ON `mydb`.* TO 'myuser'@'localhost'     | 
+--------------------------------------------------------------+ 
2 rows in set (0,00 sec)