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

Create role named roletable to allows a user to create table, Create role n...

Create role named role_table that allows a user to create tables. Using role_table allow users kripa and reena to create tables. CREATE ROLE role_table; GRANT CREATE ANY TABLE

Durability-transaction , Durability : This property necessitates that once ...

Durability : This property necessitates that once a transaction has committed, the changes made by it be never lost because of subsequent failure. Thus, a transaction is also a bas

Define rotational latency time, Define rotational latency time. The ti...

Define rotational latency time. The time spent waiting for the sector to be accessed to appear under the head is known as the rotational latency time.

Answer, Describe multi key files

Describe multi key files

Describe the most important classes of parallel machines, Question 1 Discu...

Question 1 Discuss the classification of DBMS based on location of database Question 2 Explain with examples different SQL commands used for creating and deleting relations.

Create data base table apply key and functions, CREATE YOUR DATABASE TABLES...

CREATE YOUR DATABASE TABLES Your database project must have a minimum of four tables. Include the SQL scripts used to create the tables in your documentation. Explain the tables

Online examination system project, entity relationship diagram for online e...

entity relationship diagram for online examination system

Give a sample of the dynamic model, Give a sample of the Dynamic Model. ...

Give a sample of the Dynamic Model. The sample of dynamic model is given below:  Dynamic model for the car: Brake and Accelerator            Brake or Applies Accelerator

Difference between a composite key and attribute, Question: (a) Discuss...

Question: (a) Discuss the difference between a composite key and a composite attribute. How would each be indicated in an E-R diagram? Support your answer with appropriate exam

What do you understand by acid, What do you understand by ACID? - ACID...

What do you understand by ACID? - ACID (Atomicity Consistency Isolation Durability) is a quality sought after in a reliable database. Here's the relevance of each quality:

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