Create a new database named mydb with user named mydbuser and grant all PRIVILEGES:

CREATE DATABASE mydb;
CREATE USER 'mydbuser'@'%' IDENTIFIED BY 'PASSWORD_HERE';
GRANT ALL PRIVILEGES ON `mydb`.* TO 'mydbuser'@'%';
SHOW GRANTS for 'mydbuser';
SHOW GRANTS for 'mydbuser'@'%';

Read only:

GRANT SELECT, SHOW VIEW ON `mydb`.* TO 'mydb-reader'@'%';