Answers for "mysql update column to auto_increment"

create a table with an id in mysql

CREATE TABLE DemoT (
    Personid int NOT NULL AUTO_INCREMENT,
    LastName varchar(111) NOT NULL,
    FirstName varchar(111),
    Age int,
    PRIMARY KEY (Personid)
);

add auto_increment column to existing table mysql

ALTER TABLE `users` ADD `id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY

ALTER TABLE `users` ADD `id` INT NOT NULL AUTO_INCREMENT UNIQUE FIRST