auto increment field in mysql code example

Example 1: mysql alter column auto increment

ALTER TABLE document MODIFY COLUMN document_id INT auto_increment

Example 2: 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)
);