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

Employee elation with information, Consider a database application that dea...

Consider a database application that deals with an Employee relation with information such as SIN, name, data of birth (DOB), and DID (the ID of the department at which the employe

Decompose the table with the functional dependencies, Decompose the table w...

Decompose the table with the following description and functional dependencies into a set of equivalent tables normalized to 3NF or BCNF. This database stores records from a (ve

What is meant by data-transfer rate, What is meant by data-transfer rate? ...

What is meant by data-transfer rate? The data-transfer rate is the rate at which data can be retrieved from or kept to the disk.

View serialiabilty-labelled precedence graph, how to construct labelled pre...

how to construct labelled precedence graph for view serialiability.please explain insteps with one solved examples

Improved performance, Improved performance: As the data is located near the...

Improved performance: As the data is located near the site of its demand, and given the inherent parallelism because of multiple copies, speed of database access may be good for di

find a non-redundant cover and canonical cove, Given the following set of ...

Given the following set of functional dependencies {cf→ bg, g → d, cdg → f, b → de, d → c} defined on R(b,c,d,e,f,g) a. Is cf→ e implied by the FDs? b. Is dg a superkey?

Explain concurrency control, Explain concurrency control? Concurrency ...

Explain concurrency control? Concurrency control Oracles multiversion concurrency control varies from the concurrency mechanism used by some other data base vendors. Read

Explain the exec statement in sql, Explain the EXEC statement in SQL  A...

Explain the EXEC statement in SQL  Ans: All statements which start with EXEC SQL are embedded SQL database statements. High level languages such as C can be employed to write a

Define partial, Partial Key : It is a group of attributes that can uniquel...

Partial Key : It is a group of attributes that can uniquely identify small entities and that are related to same base entity. It is sometime named as Discriminator.  Altern

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