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

Type of views-data control, Type of views :  Simple views and Difficult ...

Type of views :  Simple views and Difficult Views Feature Simple Views Complex Views Number of tables One

Define raid structure, Define raid? Briefly explain it? A range of disk...

Define raid? Briefly explain it? A range of disk organization methods, collectively called redundant arrays of independent disks (RAID) o   Improvement of reliability throug

Define rule that value of foreign key appear in other table, Determine the ...

Determine the rule that a value of a foreign key should appear as a value of some particular table is called a  Ans: Referential constraint.    The rule that a value of a fo

Normalization database, I need some help with my normalization database hom...

I need some help with my normalization database homework.

A table joined with itself is called, A table joined with itself is called ...

A table joined with itself is called ? A table joined with itself is known as self join table. Normal 0 false false false EN-IN X-NONE X-NONE

How is concurrency identified, How is concurrency identified? Concurren...

How is concurrency identified? Concurrency in objects can be identified by the way they alter their state. Current objects can change their state independently. Aggregation imp

What are the key features of oracle, What are the key features of Oracle? ...

What are the key features of Oracle? Key features of Oracle are as follows: • Read Consistency • Concurrency • Locking Mechanisms • Quiesce Database • RAC • Portability

What is structured query langauge, What is Structured Query Langauge (SQL)?...

What is Structured Query Langauge (SQL)? SQL is a powerful set-oriented language which was formed by IBM research for the databases that adhere to the relational model. It havi

Unnormalize form, employee(empid,empname,dept,telno,mobno, add,sssno,tinno,...

employee(empid,empname,dept,telno,mobno, add,sssno,tinno,WEdates,WEcomp,WEadd,WEpos,WEres) this is a employee record which is need to be normalize.the WE means work experience

Write a query to find name from the relational algebra, Consider the relati...

Consider the relations City (city_name, state) Hotel (name, address) City_hotel (hotel_name, city_name, owner) Answer the following queries in relational algebra (i) Find

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