php - 如何在mysql中使用外键state_id将表位置拆分为两个表状态，城市？

Question

我有一个表“位置”，其结构如下

CREATE TABLE IF NOT EXISTS `locations` (
`id` int(11) NOT NULL,
  `city_code` int(11) NOT NULL,
  `city_name` varchar(100) NOT NULL,
  `state_name` varchar(100) NOT NULL
) ENGINE=InnoDB  DEFAULT CHARSET=latin1 AUTO_INCREMENT=154809 ;

我想将其分成两个表:

状态包含以下字段

id,
state_name

和带有以下字段的城市

id,
state_id,
city_name,
city_code

如何在 mysql 中执行此操作。

Answer 1

创建所需的表，例如

create table states (id int not null auto_increment primary key,
                     state_name varchar(100) not null);

create table cities (id int not null auto_increment primary key,
                     state_id int not null,
                       `city_code` int(11) NOT NULL,
                       `city_name` varchar(100) NOT NULL,
                      foreign key (state_id) references states(id));

插入相应的数据

insert into states (state_name)
select state_name from locations;

insert into cities (state_id, `city_code`, `city_name`)
select s.state_id, l.`city_code`, l.`city_name`
from locations l
join states s on s.state_name = l.state_name;