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 about data independence, Data Independence This brings us to ou...

Data Independence This brings us to our next topic: data independence. It is the property of the database which tries to make sure that if we make any change in any level of sc

Develop motel point of sale software, Project Description: I need a poin...

Project Description: I need a point of sale for motels. It needs to run on windows and requires being network able so that we can have more than one computer using it at once.

Describe database state in details, Describe Database state in details? ...

Describe Database state in details? Database state: The actual data within the database at a particular moment in time is known as a database state.

Include the create database command, Submit the SQL Statements necessary to...

Submit the SQL Statements necessary to create your database according to the following guidelines: Your SQL statements should exactly mirror your ERD. All primary keys,

Designing the database schema , The domain that you will model in this assi...

The domain that you will model in this assignment is that of courses and students at a university. So as not to make the task too large and unspecified, you will here get a descrip

What is a hash index, What is a hash index? A hash index organizes the ...

What is a hash index? A hash index organizes the search keys, with their associated pointers, into a hash file structure.

Concurrency control, discuss the purpose of the concurrency control?

discuss the purpose of the concurrency control?

Which method is used to key transformation, Which method is used to key tra...

Which method is used to key transformation ? A hash method is used to key transformation.

Explain dynamic two-phase locking, Explain Dynamic Two-Phase Locking H...

Explain Dynamic Two-Phase Locking Here a transaction locks a data item instantly earlier than any operation is applied on the data item.  After finishing all the operations on

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