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

Process to find the non-concurrent objects, Process to find the non-concurr...

Process to find the non-concurrent objects Once we find out non-concurrent (mutually exclusive) objects, we can fold all objects together in one thread of process or control. O

Define a relation in dbms, Define a relation ? Relation - A relations...

Define a relation ? Relation - A relations is a named two-dimensional table of data. Mathematically, a relation can be described as a subset of the cartesian product of a lis

Write a short note on temporary tables, Write A short note on temporary tab...

Write A short note on temporary tables? Temporary Tables - Temporary tables exists solely for a particular session, or whose data persists for the duration of the transaction

What is an operand, What is an Operand? The data on which the operation...

What is an Operand? The data on which the operation is to be performed is known as an Operand

What is management system, What is Management System? A management syst...

What is Management System? A management system is a set of rules and process which help us to create organize and manipulate the database. It also helps us to add, change delet

What is functional dependency, A Functional dependency is described by ...

A Functional dependency is described by X Y between two groups of attributes Y and X that are subsets of R specifies a constraint on the possible tuple that can make a relation

Data base model, why are older data base model are being replaced by new da...

why are older data base model are being replaced by new data model

Indexed (indexed sequential) file organisation, Indexed (Indexed Sequential...

Indexed (Indexed Sequential) File Organisation It organises the file like a big dictionary, i.e., records are kept in order of the key but an index is stored which also allows

What are the properties of transaction, What are the properties of transact...

What are the properties of transaction? There are three properties of transactions :- A)     Atomicity B)      Consistency C)       Isolation

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