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

Write short notes on relational model, Write short notes on relational mode...

Write short notes on relational model   The  relational  model  uses a  collection of  tables  to show  both data  and the relationships between those  data.  The relational mo

Objectives-database recovery and security, Objectives Define the te...

Objectives Define the terms RECOVERY and INTEGRITY; Define Recovery Techniques; Explain Error and Error detection techniques, and Define types of Authorisation.

What is meant by software and hardware raid systems, What is meant by softw...

What is meant by software and hardware RAID systems? RAID can be executed with no change at the hardware level, using only software modification. Such RAID implementations are

Lack of standards and experience, Lack of standards and experience: The la...

Lack of standards and experience: The lack of standards has considerably limited the potential of distributed DBMSs. As well, there are no tools or methodologies to help users cha

Write the motivations led to development of oo-dbms, Write the motivations ...

Write the motivations led to development of OO-DBMS? 1.  Programmer frustration with RDBMSs. 2.  Requirement for special features.

What are the dbms languages, What are the DBMS languages? Explain.  Ans...

What are the DBMS languages? Explain.  Ans: a) Data Definition Languages (DDL): It is employed to specify database schema for example CREATE DROP statements etc.     b)  Dat

Synonyms and indexes, Synonyms and Indexes Some of the essential proper...

Synonyms and Indexes Some of the essential properties of indexes are: An Index is a schema Object Indexes can be formed explicitly or automatically Indexes are m

North indian plains, i am not clear with the climetic condition of the nort...

i am not clear with the climetic condition of the north indian plain. can u plz explain it for me

Data warehousing and business intelligence, I need help with data warehousi...

I need help with data warehousing and business intelligence course project about designing a data warehouse for a jewelry company that does not have one

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