How to grant privileges for a database to a user, when both already exist.
In this case the database name will be project_node1, the user project_user and the password project_pass. All the following commands have to be executed as root or with a user with enough privileges.
-- list system users
SELECT user, host FROM mysql.user;
-- see current privileges
SHOW GRANTS FOR 'project_user'@'%';
-- delete all previous privileges (if needed)
-- REVOKE ALL PRIVILEGES ON `project_node1`.* FROM 'project_user'@'%';
-- grant new privileges and flush
GRANT ALL PRIVILEGES ON `project_node1`.* TO 'project_user'@'%';
FLUSH PRIVILEGES;