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

Explain two phase locking protocol, Explain Two phase locking protocol ...

Explain Two phase locking protocol A transaction is consider as to follow the two-phase locking protocol if all locking operations precede the first unlock operation in the tra

State the rearranging the execution order for efficiency, Define the step -...

Define the step - Rearranging the Execution Order for Efficiency As we know that algorithm and data structure are closely related to one another, but data structure is conside

What is gathering information and producing erd, What is Gathering informat...

What is Gathering information and Producing ERD Gathering information: This could be a written document that explains the system in question with reasonable quantity of detai

Extended e-r features, Although, the essential features of E-R diagrams are...

Although, the essential features of E-R diagrams are enough to design many database situations. Though, with more difficult relations and advanced database applications, it is need

Example of sequences, Example : Create a sequence named SEQSS that starts a...

Example : Create a sequence named SEQSS that starts at 105, has a step of 1 and can take maximum value as 2000.  CREATE SEQUENCE SEQSS START WITH 105 INCREMENT BY 1 MAX VA

What are the advantages of relational data model, What are the advantages o...

What are the advantages of relational data model? Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer

What purpose of tables, What is the purpose of tables, private synonyms and...

What is the purpose of tables, private synonyms and public synonyms? If there are multiple objects of similar name on an Oracle database, that order are they accessed in? The r

Introduction to database technology, 1. Create the tables for the play-sche...

1. Create the tables for the play-scheme database as specified in the TMA. 2. Enter the data as given in the spreadsheet. 3. Create queries to retrieve specified information

What is secondary index, What is Secondary Index While making the index...

What is Secondary Index While making the index, generally the index table is kept in the primary memory (RAM) and the main table, because of its size is keeps in the secondary

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