Modify - referential integrity, Database Management System

Assignment Help:

Update or Modify operation alters the existing values. If these operations alter the value that is the foreign key also, the only check need is the similar as that of the Insert operation.

What should happen to an try to update a candidate key that is the objective of a foreign key reference? For instance, an attempt to update the PROJID "LG" for which there exists at least one matching ASSIGNMENT tuple? In common there are the similar possibilities as for DELETE operation:

RESTRICT: The update operation is "restricted" to the case where there are not matching assignment tuples. (it is rejected otherwise).

CASCADE - The update operation "cascades" to update the foreign key in those matching assignment tuples also.


Related Discussions:- Modify - referential integrity

Multi-list file organisation, Multi-list file Organisation Multi-list f...

Multi-list file Organisation Multi-list file organisation is a multi-index linked file organisation. A linked file organisation is a logical organisation where physical orderin

ERD, online eductional management system ke diagram

online eductional management system ke diagram

Which operator is used to compare a value to a list literals, Which operato...

Which operator is used to compare a value to a list of literals values that have been specified? BETWEEN operator is used to compare a value to a list of literals values that h

Explain how the law ensures data protection and security, Question 1: (...

Question 1: (a) Explain the legal meaning of :- (i) Computer Service Person (ii) Data holding (b) Explain how the law ensures Data protection and Security. Qu

What is relationship instance, What is relationship instance ? Relation...

What is relationship instance ? Relationship Instance - A relationship is a relation between two or more entities. An instance of relationship set is a set of relationships.

What are data models, What are data models? Explain it detail? Entity ...

What are data models? Explain it detail? Entity relationship model Rectangles Ellipse Diamonds Lines Relational model Relational model use a collection

Objectives of database manangement system, OBJECTIVES After going thro...

OBJECTIVES After going through this unit you should be capable to: Explain the File Based system and its limitations; Explain the structure of DBMS; Explain the

Illustrate the deployment diagram, Illustrate the Deployment Diagram A...

Illustrate the Deployment Diagram A deployment diagram shows all nodes on network, their processor execution and interconnections. In a dynamic model, this is used to represen

Relational declarative database language environment, Server Control It ...

Server Control It is usual to control access to the data via the front end application, for example by displaying data as ‘read only'. This part of the assignment illustrates ho

Hierarchical data representation model, Examples:- Hierarchical Model: I...

Examples:- Hierarchical Model: It tells data as and relationships by hierarchy of data values. Figure illustrates an example of hierarchical model. Now a day's these models are

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