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

Write the sql code, Express the following queries in SQL: (a) Write the...

Express the following queries in SQL: (a) Write the SQL code that will create ALL the four tables given in the appendix. Your answer should not contain the primary key and

Write short notes on relational model, Write short notes on relational mode...

Write short notes on relational model   The  relational  model  uses a  collection of  tables  to show  both data  and the relationships between those  data.  The relational mo

What is a data dictionary, What is a data dictionary?  A data dictionar...

What is a data dictionary?  A data dictionary is a data structure which keeps Meta data about the structure of the database i.e.  the schema of the database.

What is odbc and what is its function, Question: (a) What is ODBC and w...

Question: (a) What is ODBC and what is its function? (b) What is Web application server, and how does it work from a database perspective? (c) What does e-commerce mean

Er schema, Consider entity type Employee with attributes empNumber (this is...

Consider entity type Employee with attributes empNumber (this is unique), empName, and the year when he/she was hired. An employee can either be a technical employee, a marketing e

Sparse and dense indexes, Sparse and Dense Indexes These indexes in pri...

Sparse and Dense Indexes These indexes in principle are the similar as that of indexes used at the back of the book. The key facts of the indexes are: They are arranged

The extract statement do in extract datasets, What does the extract stateme...

What does the extract statement do in extract datasets? The data is written to virtual memory by extract commands.

What type of view of total database content, What type of view of total dat...

What type of view of total database content? Data base content Conceptual view of total database contain.

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