Creating views with check option-data control, Database Management System

Assignment Help:

Creating views with check option: This option limits those updates of data values that cause records to go off the view. The following instance tells this in more detail:

Example: To produce a view for employees of Department = 30, such that user cannot alter the department number from the view:

CREATE OR REPLACE VIEW EMPD30 AS

SELECT EMPNO EMPL_NUM, ENAME NAME, SAL SALARY FROM EMP

WHERE DEPTNO=30

WITH CHECK OPTION;

 

Now the user cannot alter the department number of any record of view EMPD30. If this change is permitted then the record in which the change has been made will go off the view as the view is only for department-30. This restricted due to use of WITH CHECK OPTION clause

 


Related Discussions:- Creating views with check option-data control

Explain the two types of participation constraint, Explain the two types of...

Explain the two types of participation constraint.  Total: The participation of an entity set E in a relationship set R is said to be total if each entity in E participates i

We need help in booking system for golf business, We need help in Booking S...

We need help in Booking System for Golf Business Development of a web based booking system which permits clients to book golf lessons with the following features- a) 4 user p

List the set operations of sql, List the set operations of SQL? 1) Unio...

List the set operations of SQL? 1) Union 2) Intersect operation 3) The except operation

Define serializable schedule, Define Serializable schedule Serializable...

Define Serializable schedule Serializable schedule: An interleaved schedule of much more than one transaction is known as a serializable schedule, if it is equal to some serial

Relational algebra, Consider the relation schemas as follows. works (per...

Consider the relation schemas as follows. works (person name, company name, salary); lives (person name, street, city); located in(company name, city); managers (person name

Define instance and schema, Define instance and schema?  Instance:  C...

Define instance and schema?  Instance:  Collection of  data  kept in the  data  base  at  a  particular  moment  is  known as an Instance of the database.  Schema: The o

MIS, We face problem of stock Opening balance and closing balance in Minus...

We face problem of stock Opening balance and closing balance in Minus

Sub query in the update command, Sub query in the UPDATE command : Exam...

Sub query in the UPDATE command : Example :  //Double  the  commission  for  employees,  who  have  got  at  least  2 increments. UPDATE EMP SET COMM = COMM * 2 WHERE

Datawarehouse, Explain four causes for failures in data warehouse projects

Explain four causes for failures in data warehouse projects

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