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sql server - Recursive relationship database - Database Administrators Stack Exchange

More jobs. For example, a one-to-many recursive relationship occurs when an employee is the manager of other employees. ForeignKey call, Django will set this up as a recursive relationship.

Finally we're getting to the good part! It cannot be determined ahead of time just by looking at an ER diagram.

Now consider the second example listed above: If you ignore complications where parentage is not known or legally changes, both the maternal and paternal lines are potentially infinite tree structures. A recursive relationship can be 1: Share this link with a friend: Want a remote job?

First, he wants to bundle the dial-up and Web-hosting plans and offer them at a discount, but he's not sure how to make the right table references. So this relationship is also identifying. By using this site, you agree to the Terms of Use and Privacy Policy.

A composite key is a key that is a composite of several attributes. Hierarchical queries Oracle documentation. A student can be a class monitor and handle other students. By using our site, you consent to our Cookies Policy.

Hot Network Questions. Can a customer only have one parent? One can fully understand the concepts of relationships without using or even considering those terms. It is easy to see that a "meets in" relationship between a Class entity and a Room entity cannot be satisfied between, say, two Class entities or two Room entities. HrmgmtConfig , like so: In this model, a service is composed of zero or more other services if zero, it's a simple service; if many, it's an assembly of services.

We walked through the code for defining such a recursive relationship as well as how to interact with the models to persist them to the database then how to retrieve them. In your case with Employees, the two people will continue to exist even if they lose their relationship or if the other entity is gone.

A relationship, strong or weak, demands a foreign key.