Weak entity, Database Management System

Assignment Help:

Entity types that do not have any key attribute, and therefore cannot be identified independently, are known as weak entity types. A weak entity can be recognized uniquely only by considering some of its attributes in conjunction with the primary key attributes of another entity, which is known as the identifying owner entity.

Usually a partial key is attached to a weak entity type that is used for unique identification of weak entities associated to a particular owner entity type. The following restrictions must hold:

  • The weak entity set and the owner entity set must participate in one to many relationship set. This relationship set is known as the identifying relationship set of the weak entity set.
  • The weak entity set necessary to have total participation in the recognized relationship.

 


Related Discussions:- Weak entity

Explain the terms data warehousing and data mining, Question: i) Explai...

Question: i) Explain the terms data warehousing and data mining. ii) Discuss the importance of the following security principles that a digital firm should amongst others, n

ER-diagram, The State of NewYork certifies firefighters throughout state an...

The State of NewYork certifies firefighters throughout state and keep track all of them, as well as of the state’s fire departments. Each fire department has unique department numb

Access data using logical database, If one requires to access data using...

If one requires to access data using Logical Database , the use of events is unavoidable. Yes, if someone wants to access data using Logical database then the use of events

What are the four main characteristics of the database, What are the four m...

What are the four main characteristics of the database approach? The four major characteristics of the database approach are: 1. Self-describing nature of a database system. 2.

Constraints violation during insertion, If the insertion violates one or mo...

If the insertion violates one or more constraints, then two alternatives are available: Default option: - Insertion can be discarded and the reason of refusal can also be ex

Case study, what problems are raised by the database? why is it so controve...

what problems are raised by the database? why is it so controversial? why is data quality an issue?

Eer diagram, Design an EER schema for the following application and transla...

Design an EER schema for the following application and translate the EER schema into relational schemas (and constraints). It is possible that some requirements cannot be captured

Explain what is to be done during defining problem statement, Briefly expla...

Briefly explain what is to be done during defining problem statement. To define Problem Statement of a system, define what is to be done and how you can go to implement that. Y

Lack of redundancy, Lack of Redundancy We have talked about the problems o...

Lack of Redundancy We have talked about the problems of repetition of information in a database. Such repetition should be stay away as much as possible. Let us state once again 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