Determine the strong and weak entity, Database Management System

Assignment Help:

Determine the Strong and Weak Entity

Based on the method of foreign key, there might be arise a situation when we have to relate an entity having a primary key of its own and an entity not having a primary key of its own. In such a case, the entity having its own primary key is known as a strong entity and the entity not having its own primary key is known as a weak entity. Whenever we need to relate a strong and a weak entity together, the ERD would alter just a little.

Say, for instance, we have a statement "A Student lives in a Home." STUDENT is obviously a strong entity having a primary key Roll. But HOME might not have a unique primary key, as its only attribute Address may be shared by a lot of homes (what if it is a housing estate?). HOME is a weak entity in this case.

 


Related Discussions:- Determine the strong and weak entity

Decomposition, properties of derirable decomposition

properties of derirable decomposition

Explain different types of keys and relational model., Relational Model: T...

Relational Model: The relational model uses a collection of tables to represent both data and the relationships among those data. Each table has multiple columns and each column h

Text mining, Text Processing: Use readLines to read SOU.txt into R. Cr...

Text Processing: Use readLines to read SOU.txt into R. Create a vector called Pres containing the names of the presidents giving each speech. To do this, rst identify the lin

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.

Explain record based logical models, Explain Record Based Logical Models? ...

Explain Record Based Logical Models? Record-Based logical Models: Also define data at the conceptual and view levels. Unlike object-oriented models, are used to state overall

Explain the functions trim-length-count in oracle, Explain the following fu...

Explain the following functions of Oracle with suitable examples: (i) To_Char( ) (ii) Count( ) (iii) Trim( ) (iv) Length( ) Ans: (i) To_char( ): The TO_CHAR function conver

What is middleware, Question: a) What is Client/Server and what benefit...

Question: a) What is Client/Server and what benefits can be expected from Client/Server systems? b) Explain what middleware is and what it does. Why would MIS managers be p

Write short notes on index structure of files, WRITE SHORT NOTES ON INDEX S...

WRITE SHORT NOTES ON INDEX STRUCTURE OF FILES? There are two basic parts of indices 1.   Ordered indices 2.   Hash indices Every technique must be evaluated on the bas

Can you delete data element, Can we delete data element, which is being use...

Can we delete data element, which is being used by table fields. No we cant delete data element.

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