List two restrictions that are applied on the modification, Database Management System

Assignment Help:

List two restrictions that are applied on the modification (updation, insertion or deletion) of base tables through view. 

Ans: The two restrictions are:

1. If a view does not consist of primary key and/or at least one of the attributes along with the NOT NULL constraint which do not have default values specified, is not updatable. This restriction is needed because if we are inserting any row in the view than all attributes not included in view of the base relation are will be denoted by the NULLs if any default value is not specified. In this type of case, if any attribute is set as NOT NULL or primary key, then it should not be NULL, and the insertion will be violating the constraints.

2. If a view defined by using grouping and/or aggregate functions, is not updatable. This restriction is also needed because, if we want to modify the base relation by view then we are not in the position to identify that tuple(s) will be modified in the group in what way.


Related Discussions:- List two restrictions that are applied on the modification

Cataloguing, differences between a classified catalog and a dictionary cata...

differences between a classified catalog and a dictionary catalog

Which steps must designer take to adjust inheritance, In object oriented de...

In object oriented design, which steps must designer take to adjust inheritance? To readjust inheritance following steps should be taken: i)  Rearrange and adjust the classe

Normalization, Process of normalization is the integral part of designing a...

Process of normalization is the integral part of designing a database. Justify this statement with suitable database design

Relational algebra, Relational Algebra is a set of basic operations used to...

Relational Algebra is a set of basic operations used to influence the data in relational model. These operations allow the user to specify basic retrieval request. The result of re

What is sql profiler, What is SQL Profiler? SQL Profiler is a graphical...

What is SQL Profiler? SQL Profiler is a graphical tool that permits system administrators to monitor events in an instance of Microsoft SQL Server. You can capture and save dat

Illustrate the view of software architecture, Illustrate the view of softwa...

Illustrate the view of software architecture A model is a semantically closed abstraction of system composes of elements. It can be visualized using any of the following five v

Explain difference between volatile, Explain the difference between the thr...

Explain the difference between the three storage types - volatile, non volatile and stable.             Ans: Volatile storage: if storage media loses data while power goes off,

Lack of standards and experience, Lack of standards and experience: The la...

Lack of standards and experience: The lack of standards has considerably limited the potential of distributed DBMSs. As well, there are no tools or methodologies to help users cha

Define data independence, Data independence seems that "the application is...

Data independence seems that "the application is independent of the access strategy and storage structure of data". In other words, the ability to change the schema definition in o

Authorisation, Authorisation Authorisation is the culmination of the ad...

Authorisation Authorisation is the culmination of the administrative policies of the organisation.  As the name shows, authorisation is a set of rules that can be used to verif

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