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

Illustrate how customer relationship is promoted, FitAll Ltd is a company t...

FitAll Ltd is a company that manufactures clothes. Its processes are manual and there are stand-alone Information Systems that aid to manage them. The Information Systems were purc

Draw and explain the three level architecture of database, Draw and explain...

Draw and explain the three level architecture of the database system? A DBMS gives three levels of data is said to follow three-level architecture. The trget of the three-schem

Types of locks, Types of Locks There are two necessary types of locks: ...

Types of Locks There are two necessary types of locks: Binary lock : This locking mechanism has two states for to a data item: locked or unlocked Multiple-mode loc

Report writing help on database mgmt, Report writing help on database mgmt ...

Report writing help on database mgmt Project Description: Use of Harvard referencing, critical analysis is required. Skills required: Academic Writing, Technical Writin

What is relationship instance, What is relationship instance ? Relation...

What is relationship instance ? Relationship Instance - A relationship is a relation between two or more entities. An instance of relationship set is a set of relationships.

Entity relationship diagram, The Enhanced Entity Relationship Diagram (ERD)...

The Enhanced Entity Relationship Diagram (ERD) produced with a drawing or case tool. Your EERD must use a ''standard'' notation style such as Crows Foot or Chen. Please note that t

Data aggregation, Q.   Explain  data aggregatio n and discuss differen...

Q.   Explain  data aggregatio n and discuss different design constraints. Sol. Aggregation   One limitation of the E-R model is that it cannot express relationships amon

Prepare entity relationship diagram for models your design, This project re...

This project requires you to perform a systems analysis and then design a system solution using database software. Ace Auto Dealers specializes in selling new vehicles from Subaru.

Designing the fields in the data base, Designing the fields in the data bas...

Designing the fields in the data base The following are the considerations one has to remain in mind while designing the fields in the data base. Coding, compression, en

Write short note on events, Write short note on Events Events consist ...

Write short note on Events Events consist of inputs, interrupts, decisions and actions performed by any external device or users. Every event always has a sender and receiver.

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