How to delete duplicate MySQL records with duplicate field value (as ID)

For some reason i had duplicate entries in my WP database. The ID field in wp_users table was tempered with and was changed to Non Auto-Increment to insert records on the will. I deleted all ID=null records manually and then tried to change it to AUTO INCREMENT but it came up with Duplicate Entry error and then i found that it had duplicated/multiple entries with same IDs as well. Here’s the remedy i had to apply in order to delete those duplicate entries and change ID field to AUTO INCREMENT once again.

(Note: Backup you wp_users table to avoid any mis-happening.)

bad_temp(`ID` bigint(20) unsigned NOT NULL,
`user_login` varchar(60) NOT NULL DEFAULT '',
`user_pass` varchar(64) NOT NULL DEFAULT '',
`user_nicename` varchar(50) NOT NULL DEFAULT '',
`user_email` varchar(100) NOT NULL DEFAULT '',
`user_url` varchar(100) NOT NULL DEFAULT '',
`user_registered` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
`user_activation_key` varchar(60) NOT NULL DEFAULT '',
`user_status` int(11) NOT NULL DEFAULT '0',
`display_name` varchar(250) NOT NULL DEFAULT '');

INSERT INTO bad_temp(`ID`, `user_login`, `user_pass`, `user_nicename`, `user_email`, `user_url`, `user_registered`, `user_activation_key`, `user_status`, `display_name`) SELECT DISTINCT `ID`, `user_login`, `user_pass`, `user_nicename`, `user_email`, `user_url`, `user_registered`, `user_activation_key`, `user_status`, `display_name` FROM `wp_users`;

DELETE FROM `wp_users`;

INSERT INTO `wp_users`(`ID`, `user_login`, `user_pass`, `user_nicename`, `user_email`, `user_url`, `user_registered`, `user_activation_key`, `user_status`, `display_name`) SELECT `ID`, `user_login`, `user_pass`, `user_nicename`, `user_email`, `user_url`, `user_registered`, `user_activation_key`, `user_status`, `display_name` FROM bad_temp;

DROP TABLE bad_temp;

I hope that helps someone.

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