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

What is a checkpoint, What is a checkpoint? List the operations to be perfo...

What is a checkpoint? List the operations to be performed by the system when a checkpoint is to be taken. What does the recovery system do if there is a crash? There is large n

Define the categories of sql statements, Define the categories of SQL State...

Define the categories of SQL Statements? 1) Statements that don't return a result set. This statement class includes INSERT, DELETE, and UPDATE. 2)Statements that return

Conversion of er diagram to relational database, Conversion of entity sets:...

Conversion of entity sets: I)   For  every  strong  entity  type  E  in  the  ER  diagram,  we  make  a  relation  R containing all the easy attributes of E. The relation R pri

Explain the concept of data mining, Question 1 Explain the concept of Fore...

Question 1 Explain the concept of Foreign Key. How a foreign key differs from a Primary Key? Can the Foreign Key accept nulls? Question 2 With a necessary example explain (i)

What is e-r model, What is E-R model? This data model is based on real ...

What is E-R model? This data model is based on real world that having of basic objects called entities and of relationship between these objects. Entities are explained in a da

Dependency preservation, Dependency Preservation It is obvious that the...

Dependency Preservation It is obvious that the decomposition must be lossless so that we do not lose any information from the relation that is decomposed. Dependency preservati

Dataware house, ) Define a job scheduling strategy that will meet business ...

) Define a job scheduling strategy that will meet business requirement of reporting availability by 6am CST for the following cubes? Show the job scheduling dependencies in a picto

Introduction to Database Design and Development, Every School has many teac...

Every School has many teachers and many students. Each student is assigned to one school and each teacher works for one school only. Each teacher teaches more than one subject but

What are the uses of functional dependencies, What are the uses of function...

What are the uses of functional dependencies? To test relations to see whether they are legal under a given set of functional dependencies. To state constraints on the set

What is conceptual model, What is conceptual model ? A conceptual model...

What is conceptual model ? A conceptual model is a independent of both hardware and software.

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