how to make a key autoincrement and primary key mysql code example

Example 1: set id count mysql

ALTER TABLE name AUTO_INCREMENT=310;

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)
);