mysql 创建表和外键

mysql> create table country(
　　　> country_id smallint unsigned not null auto_increment,
　　　>country varchar(50) not null,
　　   >last_update timestamp not null default current_timestamp on update current_timestamp,
　　   >primary key (country_id)
　　　>)engine=InnoDB default charset = utf8;

 

 

 

 

mysql>create table city(

　　>city_id smallint unsigned not null auto_increment,
　　>city varchar(50) not null,
　　>country_id smallint unsigned not null,
　　>last_update timestamp not null default current_timestamp on update current_timestamp,
　　>primary key (city_id),
　　>key idx_fk_country_id (country_id),
　　>foreign key (country_id) references country (country_id)
　　>ON UPDATE CASCADE ON DELETE RESTRICT
　　>) ENGINE = InnoDB default charset=utf8;