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

Naïve bayesian approach-id3 algorithm, You are working for the ABC Telecom ...

You are working for the ABC Telecom and are given some customer records for data mining. You are asked to discover, from the data, patterns that characterize low-, medium- and high

What are data models, What are data models? Explain it detail? Entity ...

What are data models? Explain it detail? Entity relationship model Rectangles Ellipse Diamonds Lines Relational model Relational model use a collection

What is thread splitting, What is Thread splitting A thread of cont...

What is Thread splitting A thread of control is a path by which a set of state diagrams on that a single object is active at a time. Objects are shared between threads

Many-to-many relationship, For each m:n relationship type R, we make a new ...

For each m:n relationship type R, we make a new table (say S) to represent R. We also contain the primary key attributes of both the participating entity types as a foreign key att

Mappings between levels and data independence, Mappings between Levels and ...

Mappings between Levels and Data Independence The 3 levels of abstraction in the database do not exist separately of each other. There must be some correspondence, or mapping

B-tree, construct a b-tree for the following set of key values 2,3,5,7,11,1...

construct a b-tree for the following set of key values 2,3,5,7,11,17,19,23,29,31.assume that the tree is initial empty and the values are added in ascending order

Define decision tree classifiers, Define decision tree classifiers? As ...

Define decision tree classifiers? As the name suggests decision tree classifiers use a tree: Every leaf node has an associated class, and every internal node has a predicate as

Prepare a site map and submit it in bing and google, Project Description: ...

Project Description: I am updating my Javascript + HTML website with five domains for the same website I would like to know if I want to create site map and submit it in all the

Give two profit of reuse of code, Give two profit of Reuse of Code. Re...

Give two profit of Reuse of Code. Reusing the implementation . Place existing class directly inside a new class. The new class can be made up of any number and type of the oth

Participation constraints, The participation Constraints shows whether the ...

The participation Constraints shows whether the existence of an entity depends on its being associated to another entity by the relationship type. There are two kinds of participat

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