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

Modular growth, Modular growth: In distributed environments, it is simple t...

Modular growth: In distributed environments, it is simple to expand. Latest sites can be added to the network without affecting the operations of other sites, as they are somewhat

Explain olap and the benefits of olap, Data Mining 1. What is data mini...

Data Mining 1. What is data mining? Write Data Mining applications. 2. Explain OLAP? Write the benefits of OLAP. 3. What are the key features of a Data Warehouse? 4. W

Central database schema, Show a centralised schema to support the operation...

Show a centralised schema to support the operation of the system you have chosen, including in particular: the product catalogue; the outlets and respective stocks; customer record

Logical entity relationship diagrams, How can i turn a conceptual entity re...

How can i turn a conceptual entity relationship diagram into a logical entity relationship diagram? what do i have to do with "mandetory or" and "optional or" relationships?

Correlated and uncorrelated queries, need to get answer for questions 3&4 o...

need to get answer for questions 3&4 on this page in part 1

What is called as recursive partitioning, What is called as recursive parti...

What is called as recursive partitioning? The system repeats the splitting of the input unless each partition of the build input fits in the memory. Such partitioning is known

A table joined with itself is called, A table joined with itself is called ...

A table joined with itself is called ? A table joined with itself is known as self join table. Normal 0 false false false EN-IN X-NONE X-NONE

File manager-database management system, File Manager File manager ha...

File Manager File manager handles the allocation of space on disk storage. It starts and maintains the list of structures and indices described in the internal schema that is

Stored and derived attributes, Attributes that are directly kept in the dat...

Attributes that are directly kept in the data base. For example, 'Birth date' attribute of a person.   Derived  Attributes that are not stored directly but can be derived

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