Mysql add fields to modify deleted columns

1, add fields (alter, add)

mysql> alter table users add name varchar(30) not null after id;

2, modify the field (alter, modify / change)

mysql> alter table users modify telno int unsigned default '0';

alter table users change telno phone int unsigned default '0';

The difference between modify and change: change field names can be modified, modify not

3, delete the field (alter, drop)

mysql> alter table users drop name;

4, rename table (rename as)

mysql> alter table users_new rename as users;

5, delete the table (drop)

mysql> drop table if exists users;