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 are the desirable properties of a decomposition, Define What are the d...

Define What are the desirable properties of a decomposition Ans: What are the desirable properties of decomposition - dependency preserving.  Because Lossless join and dependen

Define average seek time, Define average seek time. The average seek ti...

Define average seek time. The average seek time is the average of the seek times, calculated over a sequence of random requests.

Product adder required for ecommerce website, Product adder required for Ec...

Product adder required for Ecommerce website Project Description: Want a product adder for 500 products I have a magento website and need products pulled from site A to my si

What are composite attributes, What are composite attributes? Composite...

What are composite attributes? Composite attributes can be separated in to sub parts.

Differentiate between a global and a local temporary table, Differentiate b...

Differentiate between a Global and a Local temporary table? - A local temporary table exists only for the duration of a connection or if defined inside a compound statement, fo

Describe application programming interface, Describe Application programmin...

Describe Application programming interface? Application Programming Interface - Commercial SQL implementations take one of the two primary techniques for involving SQL in a p

Mapping, external and internal mapping with examples

external and internal mapping with examples

Increased parallelism-data replication, Increased parallelism : Since the r...

Increased parallelism : Since the replicated date has several copies a query can be distributed or can be answered from the smallest loaded site. Also, with more replicas you have

Original Database, I need an ERD created for any original database(can be o...

I need an ERD created for any original database(can be on anything). It needs to be 3NF. I then need all the CREATE STATEMENTS, INSERT STATEMENTS(anything you can think of as long

Large Project, Can you help me with the following: Drop statements for all...

Can you help me with the following: Drop statements for all objects in the lab project. Create statements for all objects of the lab project Create indexes for foreign keys Cre

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