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mysqlsqldatabasejoinrelational-database
Weacked
Weacked

Reputation: 970

How to store a one to many relation in MySQL database?

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

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

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

Upvotes: 17

Views: 33813

Answers (2)

Björn
Björn

Reputation: 29381

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`)
);

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`

Upvotes: 36

Fábio Nicolau de Lima
Fábio Nicolau de Lima

Reputation: 1494

I think you need to create a one to many relationship table.

You can see more infos here: http://dev.mysql.com/doc/workbench/en/wb-relationship-tools.html

Upvotes: 0

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