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

Clustering indexes, Clustering Indexes It may be an excellent idea to k...

Clustering Indexes It may be an excellent idea to keep data of the students in the order of the programme they have registered as most of the data file accesses may need studen

What are audit trails, What are audit trails? An audit trail is a log o...

What are audit trails? An audit trail is a log of all alters to the database along with information like which user performed the change and when the alter was performed.

The transactions, The Transactions- A transaction is definite as the unit o...

The Transactions- A transaction is definite as the unit of work in a database system. Database systems that deal with a huge number of transactions are also termed as transaction p

Why do you go for sorting your query results, Why do you go for sorting you...

Why do you go for sorting your query results? SQL SELECT command to fetch data from MySQL table. Whenever you select rows, the MySQL server is free to return them in any order

List the requirements needed to design a trigger, List the requirements nee...

List the requirements needed to design a trigger. The requirements are:- Specifying when a trigger is to be implemented. State the actions to be taken when the trigger im

ERD, A student entity type has the following attributes,name..

A student entity type has the following attributes,name..

What is a query tree, What is a query tree?     Ans:  A query tree, as ...

What is a query tree?     Ans:  A query tree, as well known as operator graph, is a tree data structure that corresponds to a relational algebra expression. It denotes the inpu

What are the responsibility of file manager, What are the responsibility of...

What are the responsibility of File manager? File Manager : Manager allocation of space on disk storage and the data structures used to represent within stored on disk. It is a

What is oracle process explain for processes of oracle, What is Oracle Proc...

What is Oracle Process? Explain any four processes started by Oracle. Oracle Process is as follows: SMON: The System Monitor carries out a crash recovery while a crashed in

Hashing techniques, folding method and mid square method using visual basic...

folding method and mid square method using visual basic

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