如何在 MySQL 数据库中存储一对多关系?

问题描述

我正在制作一个网站，我需要在我的数据库中存储随机数量的数据.

I'm making a website and I need to store a random number of data in my database.

例如，用户 john 可能有一个电话号码，而 jack 可能有 3 个.

For example, User john may have one phone number where jack can have 3.

我需要能够为每个用户存储无限数量的值.

I need to be able to store an infinite number of values per user.

推荐答案

您为电话号码创建一个单独的表(即 1:M 关系).

You create a separate table for phone numbers (i.e. a 1:M relationship).

create table `users` (
  `id` int unsigned not null auto_increment,
  `name` varchar(100) not null,
  primary key(`id`)
);

create table `phone_numbers` (
  `id` int unsigned not null auto_increment,
  `user_id` int unsigned not null,
  `phone_number` varchar(25) not null,
  index pn_user_index(`user_id`),
  foreign key (`user_id`) references users(`id`) on delete cascade,
  primary key(`id`)
);

现在，您可以通过简单的连接轻松获取用户的电话号码；

Now you can, in an easily manner, get a users phone numbers with a simple join;

select
  pn.`phone_number`
from
  `users` as u,
  `phone_numbers` as pn
where
  u.`name`='John'
  and
  pn.`user_id`=u.`id`

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