What is foreign key, Database Management System

Assignment Help:

What is foreign key?

A relation schema r1 derived from an ER schema may contain among its attributes the primary key of another relation schema r2.this attribute is known as a foreign key from r1 referencing r2.  

 


Related Discussions:- What is foreign key

File manager-database management system, File Manager File manager ha...

File Manager File manager handles the allocation of space on disk storage. It starts and maintains the list of structures and indices described in the internal schema that is

Why as clause is used in sql, Why 'AS' clause is used in SQL ? 'As' cla...

Why 'AS' clause is used in SQL ? 'As' clause is used for Rename operation. ‘AS' clause is used in SQL for rename operation. (e.g., SELECT ENO AS EMPLOYEE_NO FROM EMP)

What are the various symbols used to draw an e-r diagram, What are the vari...

What are the various symbols used to draw an E-R diagram? Explain with the help of an example how weak entity sets are represented in an E-R diagram. Various symbols used to d

Weak entity, An example of a weak entity is Staff because the availabilityI...

An example of a weak entity is Staff because the availabilityID cannot be uniquely identified unless it is used in conjunction with the foreign key known as availabilityID in the A

Define the term- making common behaviour abstract, Making Common Behaviour ...

Making Common Behaviour Abstract Let us define abstraction "Abstraction means to focus on the necessary, inherent aspects of an entity and ignoring its accidental features". O

Define hot swapping, Define hot swapping? Hot swapping permits the remo...

Define hot swapping? Hot swapping permits the removal of faulty disks and changes it by new ones without turning power off. Hot swapping decreases the mean time to repair.

B+ tree, construct a B+ tree for the following set of key value (2,3,5,7,11...

construct a B+ tree for the following set of key value (2,3,5,7,11,19,23,29,31) in ascending order where the pointers that will fit in one node is as follows:A. four B. six C. eigh

Computing the closure of a set of functional dependency, What is meant by c...

What is meant by computing the closure of a set of functional dependency? The closure of F denoted by F + is the set of functional dependencies logically implied by F.

Integrity of a database enforced by integrity rules, Question: This Que...

Question: This Question refers to the database schema given in the Appendix. (a) The integrity of a database is enforced by integrity rules. Discuss what should happen on a

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