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

Back up files, what is the importance of back up files

what is the importance of back up files

Explain hierarchical model, Explain Hierarchical Model ? Hierarchical ...

Explain Hierarchical Model ? Hierarchical Model - It was established to model several kinds of hierarchical organizations which exist in the real world. It uses tree structur

What is called as recursive partitioning, What is called as recursive parti...

What is called as recursive partitioning? The system repeats the splitting of the input unless each partition of the build input fits in the memory. Such partitioning is known

Explain the internal architecture of 8086, Problem 1. Write an assembly...

Problem 1. Write an assembly program to find the smallest among two numbers Writing an assembly program to find the smallest among two numbers 2. Explain the intern

The first normal form (1nf), The First Normal Form (1NF) Let us first d...

The First Normal Form (1NF) Let us first describe 1NF: Definition: A relation (table) is in 1NF if 1.      There are no duplicate tuples or rows in the relation. 2.

relationship with the owner entity, A database for the Service and Mainten...

A database for the Service and Maintenance (SM) section of a Computer sales and service Company has to be developed. SM gives after sales service to customers. SM branch has a numb

Define object-oriented database, Question : Object-Oriented Database (O...

Question : Object-Oriented Database (OODM) is defined as a logical data model that captures the semantics of objects supported in object-oriented programming. An Object-Oriente

Benefits abd drawback of hashed file organisation, Benefits of Hashed file ...

Benefits of Hashed file Organisation 1.      Insertion or search on hash-key is quick. 2.      Best if equality search is required on hash-key. Drawbacks of Hashed file

Define data independence, Data independence seems that "the application is...

Data independence seems that "the application is independent of the access strategy and storage structure of data". In other words, the ability to change the schema definition in o

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