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

Define and differentiate among ordered indexing and hashing, Define and dif...

Define and differentiate between ordered indexing and hashing. Ans: Ordered indexing: To gain fast random access to records in a file, we can make of an index structure. Every

Answer, what is database management system? & why it is required?

what is database management system? & why it is required?

Define direct file organization, Define Direct file organization? The d...

Define Direct file organization? The direct file organization is employed to enhance the performance in accessing the records than sequential file organization. In direct file

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

Reasons for the growing popularity of data mining, Question: Data Minin...

Question: Data Mining is the process of extracting knowledge hidden from large volumes of raw data. (a) Using a suitable example, illustrate how Data Mining can be useful t

Remove all transitive dependencies - dependency diagram, 1. Use the Invoice...

1. Use the Invoice table structure shown below to answer the following questions: a)  Draw the dependency diagram and identify the primary key and all dependencies, including al

Explain er model, Question 1 Explain ER model Question 2 What are the...

Question 1 Explain ER model Question 2 What are the characteristics of a computer provided information? Question 3 What are facts and guidelines to be considered when se

What is dml (data manipulation language)?, This language that enable user m...

This language that enable user manipulate to or access data as organized by appropriate data model. Low level or Procedural DML : DML needs a user to specify what data ar

Homework, can you resolve this for me please? Database Management Systems ...

can you resolve this for me please? Database Management Systems Homework 1 The following relations are given (primary keys are underlined): PLAY-ACTOR(AId, Name, Nationality, Birt

Compare the efficiency of the two mining processes, Consider the following ...

Consider the following database containing five transactions. Let min_sup = 60%. Mine all frequent itemsets using Apriori and FP-growth algorithm. Compare the efficiency of the t

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