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

Differance between unordered and ordered file, Differance between Unordered...

Differance between Unordered and ordered file ? Unordered file do no has any sequence although ordered file has arranged in a few sequence and data are assigned in ordered form

Describe the iterative and incremental life cycle, Describe the iterative a...

Describe the iterative and incremental life cycle For an iterative and incremental life cycle, two criteria are process and time. The main components of showing a project devel

Explain foreign key, Explain Foreign Key? Foreign Key - Let there are...

Explain Foreign Key? Foreign Key - Let there are two relations (tables) R and S. Any candidate key of the relation R that is referred within the relation S is known as the fo

What is the state machine engine, What is the State Machine Engine The...

What is the State Machine Engine The straightest approach to implement control is to have any way of explicitly representing and executing state machines. With the help of thi

List and also explain the dissimilar stages of ddlc, List and also explain ...

List and also explain the dissimilar stages of DDLC ?

Determine the strong and weak entity, Determine the Strong and Weak Entity ...

Determine the Strong and Weak Entity Based on the method of foreign key, there might be arise a situation when we have to relate an entity having a primary key of its own and a

What is data integrity, What is data integrity? Ans: It is the data con...

What is data integrity? Ans: It is the data consisted of in database that is accurate and consistent.  (Data integrity means that the data should be valid as per to the give

Define catalog and meta data, Define Catalog and meta data ? A catalog ...

Define Catalog and meta data ? A catalog is a compilation of records elaborating the contents of a particular collection or group of collections. Metadata (Meta data, or someti

Construct a generalization-specialization hierarchy, Construct a generaliza...

Construct a generalization-specialization hierarchy for a motor-vehicle sales company. The company sells motorcycles that comprise an engine number and cost; cars that have a chass

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