ERROR 1396 (HY000): Operation CREATE USER failed for 'username'@'localhost' IDENTIFIED BY 'mypassword';

Question

Mistakenly I deleted my root user from my mysql.user table.

delete from mysql.user where user=\'username\';

To make same root

Answer 1

If you use DROP USER command to remove the user, then the user gets removed completely. If you have to add user with same username later, you can use FLUSH PRIVILEGES command to completely remove privileges from the mysql memory.

DROP USER username@hostname;

You have to restart mysql or run FLUSH PRIVILEGES before creating the same user because there are issues with privileges. To restart mysql in linux based systems

sudo service mysql restart

to restart in windows systems

net stop mysql
net start mysql

To flush privilege in mysql prompt

FLUSH PRIVILEGES;

You can alternatively use REVOKE command if you know which privileges that the user has

REVOKE privillege1, privillege2, ... FROM deleted_user@host

Answer 2

As for the above, password field does not exist in my case and mysql throws an error.

This command helped:

INSERT INTO mysql.user (user, host, ssl_cipher, x509_issuer, x509_subject, plugin, authentication_string) VALUES ('user', 'localhost', '', '', '', 'mysql_native_password', PASSWORD('pass'));

Answer 3

This user must be referenced in other tables from the mysql system schema. I would recreate the user the same way you deleted it:

INSERT INTO mysql.user (user, host, password)
VALUES ('root', 'localhost', PASSWORD('pasw'));

Then

FLUSH PRIVILEGES;
GRANT ALL ON *.* TO 'root'@'localhost';

Yet another reason to never mess with this schema (sorry, I couldn't help).