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

Wound-wait scheme-deadlock prevention, " Wound-wait" scheme : It is based o...

" Wound-wait" scheme : It is based on a preemptive method. It is based on a simple rule:                   If Ti requests a database resource that is held by Tj

What is derived and stored attribute, What is Derived and stored Attribute?...

What is Derived and stored Attribute? Derived and Stored Attribute - In a few cases, two or more attribute values are associated, for example, Age and BirthDate attributes of a

Explain the term- query, Explain the term- Query. Queries are used to re...

Explain the term- Query. Queries are used to repossess and show specific records in a table. They can also be used to show specific fields of specific records, which meet the co

To eliminate duplicate rows-data manipulation language, To eliminate duplic...

To eliminate duplicate rows (distinct operator)  Example: SELECT DISTINCT DEPTNO FROM EMP;

Express types of information available in mysql, Express types of informati...

Express types of information available in MySQL? Information as regards the result of queries:  This includes number of records affected by any SELECT or UPDATE or DELETE st

What is database utility, What is database utility? Database utility is...

What is database utility? Database utility is the interface among the ABAP/4 Dictionary and the underlying the SAP system.

Explain the concept of a data model, Explain the concept of a data model ? ...

Explain the concept of a data model ? Data Model - Model is an abstraction procedure which hides irrelevant details although highlighting details relevant to the application

Which language has recently become the defacto standard, Which language has...

Which language has presently become the defacto standard for interfacing application programs along with relational database system? The language which has recently become the

Develop a simple database of student records, In this programming assignmen...

In this programming assignment, you will develop a simple database of student records. Here are the requirements: 1) A student record contains a name and a number. We assume tha

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