There are entities Customers and Services. A client may use several services, but “The service may be provided to several clients.” A “many-to-many” connection is obtained.
How to split it into one to many?

  • And why do you need to "crush" if not a secret? - Kirill Novikov
  • @Radik Kamalov, If you are given an exhaustive answer, mark it as correct (click on the check mark next to the selected answer). - Deleted

1 answer 1

Add a third customer service entity, and associate it with each of the others.

  • 2
    +1 is called the link table. - Yura Ivanov
  • 3
    Yes that's right. The only thing that from the point of view of the real world should be the essence of the Provision of Service (Order, Outfit ...) which reflects the actual fact of providing a particular service to a specific client. Well, there still specify the date, cost, etc. - SilverIce
  • Those. is it a magazine (customer record for the service)? - Radik Kamalov
  • one
    It depends on what is meant by the word "journal". The main thing is that this entity has a composite primary key, each part of which is a foreign key to the entity being linked through it. - msi