Mysql create user, allow access to DB, allow access DBs by prefix and wildcard

https://alvinalexander.com/blog/post/mysql/show-users-i-ve-created-in-mysql-database
https://www.digitalocean.com/community/tutorials/how-to-create-a-new-user-and-grant-permissions-in-mysql

Copy, clone (duplicate) whole database:
https://stackoverflow.com/questions/1887964/duplicate-entire-mysql-database

CREATE DATABASE duplicateddb;
Make sure the user and permissions are all in place and:

 mysqldump -u admin -p originaldb | mysql -u backup -pPassword duplicateddb; 

MySQL password policy validation:

https://stackoverflow.com/questions/43094726/your-password-does-not-satisfy-the-current-policy-requirements?rq=1

ERROR 1819 (HY000): Your password does not satisfy the current policy requirements

It seem MySQL new (?) password validation ?

I tried few password and end up with a password length about 10 character, 1 Capical, some number and a special char, something like this:

Cmypass_1234

Allow access to databases by prefix and then wildcard:
https://stackoverflow.com/questions/5988842/can-i-grant-access-to-databases-with-prefix-then-wild-card

GRANT ALL PRIVILEGES ON  `jaap\_%` . * TO  'jaap'@'localhost';

You can see that, best way (for security or safety) we should have separate DB access to separate user. This way require more time to create user, config, especially on Test server where many sites and DB hosted here.
Use prefix and wildcard is a middle balance way.