Explain weak and strong entity type, Database Management System

Assignment Help:

Explain weak and strong entity type ?

Weak and Strong entity type: An entity set which does not have a primary key is referred to as a weak entity set. The existence of a weak entity set depends on the existence of a strong entity set; it must associate to the strong set via a on-to-many relationship set. A discriminator of a weak entity set is the set of attributes that distinguishes between all the entities of a weak entity set. The primary key of a weak entity set is formed by the primary key of the strong entity set on that the weak entity set is existence depends, plus the weak entity set's discriminator.


Related Discussions:- Explain weak and strong entity type

Special comparison operator used in where clause-dml, Special comparison op...

Special comparison operator used in where Clause a.   between. ...and...It gives range among two values (inclusive) Example: SELECT ENAME, SAL FROM EMP WHERE SAL BETWE

Explain the need of parallel database, Probelm: a) In the context of OO...

Probelm: a) In the context of OODBMS, define the following terms with appropriate examples. (i) Object class. (ii) Abstract class. (iii) Aggregation. (iv)

What is called as an n-way merge, What is called as an N-way merge? The...

What is called as an N-way merge? The merge operation is a generalization of the two-way merge used by the standard in-memory sort-merge algorithm. It merges N runs, so it is k

What is called a query -execution engine, What is called a query -execution...

What is called a query -execution engine? The query implementation engine takes a query evaluation plan, implements that plan, and returns the answers to the query.

Define the one-way associations, One-way Associations When an associat...

One-way Associations When an association is traversed only in the one direction, then it is implemented as a pointer i.e.an attribute which contains an object reference. If mu

Non-query optimisations, Part: Recommended (Non-query) Optimisations Thi...

Part: Recommended (Non-query) Optimisations This section entitled "Recommended (non-query) optimisations" should be a brief report containing recommended optimisations you would

Post vbulletin hack and new server problem, Project Description: My VBul...

Project Description: My VBulletin forum was hacked, and soon after my server machine died. So, I'm now on a new machine, and I think that I've taken care of 99% of the hacking..

Insert - referential integrity, The insertion of a tuple in the aim of refe...

The insertion of a tuple in the aim of reference does not cause any destruction. Though, insertion of a tuple in the relation in which, we has the foreign key, for instance, in ASS

List the steps for converting state diagram to the code, List the steps for...

List the steps for converting state diagram to the code. a) Finding major control path b) Finding the conditional statements  c) Finding the loops  d) Finding error ro

What is difference between primary index and secondary index, What is diffe...

What is difference between primary index and secondary index? Primary Index a) It is an ordered file whose records are of fixed length along with two fields. b) Only base

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