“IDENTIFIED BY 'password'” in MySQL

问题:

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?

回答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'; 

回答2:

As grant self created user so, below line is enough for rights-

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

Note: Identify represents to your password what password you want to save for credential verification.

回答3:

It's just an added security measure. You might have different passwords for the same user on different servers, for example in a shared host environment. If it's your own server and you and your colleagues are the only ones who use it then you don't need to identify the users you grant privileges to.

If you identify users then only the password you specify can be used with that user to perform those privileges.

回答4:

Code below gives full access to all databases. Other commands mentioned in answers are work if you have the specific databases in the mysql server. Code below is works regardless of the state in which the server is in. Just login to the linux server -> type mysql and enter:

GRANT ALL privileges ON *.* TO 'user'@'host'  identified BY 'password';