GRANT ALL PRIVILEGES ON a*.* TO 'my_user'@'%' WITH GRANT OPTION;
Yes, you can.
This is what phpMyAdmin does when I make a user
jaap and use the option
Grant all privileges on wildcard name (username\_%):
GRANT ALL PRIVILEGES ON `jaap\_%` . * TO 'jaap'@'localhost';
That's what you mean, right?
As you can see, the
_ is escaped, because in (My)SQL an unescaped
_ means 'one character'. (Like
. in regex.) In this case, you want the
_ to be literal, so databases must start with