What is a foreign key, Database Management System

Assignment Help:

What is a foreign key, and what is it used for?

A foreign key is used to establish relationships between relations in the relational model. Technically, a foreign key is a column (or columns) appearing in one relation that is (are) the primary key of another table. Although there might be exceptions, the values in the foreign key columns usually must correspond to values existing in the set of primary key values. This correspondence necessity is created in a database using a referential integrity constraint on the foreign key.

 

 


Related Discussions:- What is a foreign key

Greater potential for bugs and increased processing overhead, Greater poten...

Greater potential for bugs: Since the sites of a distributed system operate simultaneously, it is more complex to ensure the correctness of algorithms. The art of constructing dis

Describe database state in details, Describe Database state in details? ...

Describe Database state in details? Database state: The actual data within the database at a particular moment in time is known as a database state.

What is repository?, Problem 1 Why are the operational system keys not ...

Problem 1 Why are the operational system keys not recommended for forming data warehouse primary keys? Give any two examples 2 Explain the following performance tuning techn

Deadlock and its prevention, Deadlock And Its Prevention: As seen earlier,...

Deadlock And Its Prevention: As seen earlier, though two phase locking protocol handles the trouble of serialisability, but it causes some troubles also. For instance, consider th

Aims of the design project, The aims of the project are: 1. To enable th...

The aims of the project are: 1. To enable the students to undertake the detailed design of a specific plant or process 2. The design projects includes: process selection; und

Explain the concept of deadlock, Explain the concept of deadlock Yes. I...

Explain the concept of deadlock Yes. It can direct to deadlock. Suppose that a batch of frames arrived correctly and were accepted. Then receiver will advance its window. Now s

Note gate, i want notes on this topic

i want notes on this topic

The basic 2pl-two phase locking (2pl), Normal 0 false false ...

Normal 0 false false false EN-US X-NONE X-NONE

Insertion anomaly-data redundancy, Insertion Anomaly: Inability to show ce...

Insertion Anomaly: Inability to show certain information-The primary key of the over relation be (enrolment number, Cno). Any new tuple to be inserted in the relation should have

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd