Modify - referential integrity, Database Management System

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.

Posted Date: 3/6/2013 6:39:41 AM | Location : United States







Related Discussions:- Modify - referential integrity, Assignment Help, Ask Question on Modify - referential integrity, Get Answer, Expert's Help, Modify - referential integrity Discussions

Write discussion on Modify - referential integrity
Your posts are moderated
Related Questions
a) Distinguish between ‘database' and ‘Database Management Systems (DBMS)'. b) List and briefly describe five potential benefits of the database approach compared to conventio

Describe the nested-loop join and block-nested loop join.   Ans:   The block nested- loop join algorithm is as described below:     for every block B r of relation R do beg

Question 1 What do you mean by database management system? Question 2 Write a note on Object-Oriented Model Question 3 Explain Sequential File Organization Question

#question.what is mapping constraints and types?.

What do you mean by atomicity and aggregation? Atomicity : Either all actions are carried out or none are. Users should not have to worry about the effect of incomplete trans

What is known as a search key? An attribute or set of attributes used to look up records in a file is known as a search key.

What are the functions of an accumulator? The accumulator is the register associated with the ALU operations and sometimes I/O operations. It is an integral part of ALU. It hol

What is Cross Product? Simply Cross product is Binary Operator

Prepare a data flow diagram for computing the volume and surface area of a cylinder. Inputs are the height and radius of the cylinder. Outputs are the volume and surface area of th

Define canonical cover? A canonical cover Fc for F is a set of dependencies like F logically implies all dependencies in FC and Fc logically shows all dependencies in F.