Question

I have three tables:

1. User (id, name, birthdate) – PRIMARY KEY (‘id’)

2. Contact ( id, contact, verified ) – PRIMARY KEY (‘id’)

3. UserContact ( User_id, Contact_id ) – No Primary Key or Foriegn Key

Problem is that I did not care of primary key or foreign key while creating UserContact table. Therefore I am getting following error while inserting record in UserContact table in zend framework.

A table must have a primary key, but none was found

Now I want to create a MySql script that alter UserContact table and make User_id and Contact_id as foreign keys from User and Contact tables. How to write this script. I am using phpMyAdmin.

Thanks

Answer 1

ALTER TABLE Syntax

Add foreign keys –

ALTER TABLE UserContact
  ADD CONSTRAINT FK_UserContact_User FOREIGN KEY (user_id) REFERENCES user(id);
ALTER TABLE UserContact
  ADD CONSTRAINT FK_UserContact_Contact FOREIGN KEY (contact_id) REFERENCES user(id);

Add primary key –

ALTER TABLE UserContact
  ADD PRIMARY KEY (User_id, Contact_id);