privileges - "IDENTIFIED BY 'password'" in MySQL

Question

I often see in many MySQL tutorials that people use command IDENTIFIED BY 'password' both during user creation and granting him privileges.

For example:

CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';
GRANT ALL PRIVILEGES ON database.* TO 'username'@'localhost' IDENTIFIED BY 'password';

I tried using GRANT without IDENTIFIED BY and it works.
Can somebody explain me why it is used twice? Could there be other password for specific privileges?

Answer 1

GRANT is meant for adding privileges to users. Confusingly, it also has the ability to create users and change their passwords. This functionality is deprecated and should not be used.

If you use GRANT with IDENTIFIED you can change the user's password:

When IDENTIFIED is present and you have the global grant privilege (GRANT OPTION), any password specified becomes the new password for the account, even if the account exists and already has a password. Without IDENTIFIED, the account password remains unchanged.

As of MySQL 5.7.2, if the account already exists, IDENTIFIED WITH is prohibited because it is intended only for use when creating new accounts.

Also, GRANT may create the user if it does not exist:

If an account named in a GRANT statement does not exist, the action taken depends on the NO_AUTO_CREATE_USER SQL mode:

• If NO_AUTO_CREATE_USER is not enabled, GRANT creates the account. This is very insecure unless you specify a nonempty password using IDENTIFIED BY.
• If NO_AUTO_CREATE_USER is enabled, GRANT fails and does not create the account, unless you specify a nonempty password using IDENTIFIED BY or name an authentication plugin using IDENTIFIED WITH.

Use of GRANT to define account authentication characteristics is deprecated as of MySQL 5.7.6. Instead, establish or change authentication characteristics using CREATE USER or ALTER USER. This GRANT capability will be removed in a future MySQL release.

See https://dev.mysql.com/doc/refman/5.7/en/grant.html

In summary, use CREATE to create a user, and use GRANT to add privileges:

CREATE USER 'username'@'localhost' IDENTIFIED BY 'password';
GRANT ALL PRIVILEGES ON database.* TO 'username'@'localhost';