Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Explain entity integrity and referential integrity rules within relational model. Show how these are realized in SQL?
Entity Integrity Rule - No primary key value could be null.
Referential Integrity Rule - In referential integrity, it is ensured in which a value which appears in one relation for a given set of attributes also appears for a certain set of attributes within another relation.
In SQL, entity integrity and referential integrity rules are implemented as constraints on the relation known as primary key constraint or reference key constraint corresponding. These constraints can be specified along with relation at the time of creation of the relations or after the creation of the relations through altering the definition of the relations. For instance:
CREATE TABLE DEPT
(DEPTNO NUMBER PRIMARY KEY,
DNAME VARCHAR2(15));
CREATE TABLE EMP
(EMPNO NUMBER PRIMARY KEY,
20
ENAME VARCHAR2(15),
JOB VARCHAR2(10),
DEPTNO NUMBER REFERENCES DEPT(DEPTNO));
During the deletion of a tuple two cases can happen: Deletion of tuple in relation having the foreign key: In this type of case simply delete the desired tuple. For example, in
Though all the ABAP/4 Dictionary Structures that exists in the structure of the LDB, being described in Database Program, we are explaining the Dictionary Structures in the Report.
What is OMR? OMR (Optical Mark Recognition) is the translation of marks - or the absence of marks - but not the shape of the mark on forms that have small circles ("also called
Consider the relations EMP(ENO,ENAME,AGE,BASIC_SALARY) WORK_IN(ENO,DNO) DEPT(DNO,DNAME,CITY) Express the following queries in SQL (i) Find names of employees who work in a dep
This report identifies and outlines my CIS 499 project named Traffic Data Management Systems (TDMS) . My goal is to design a replica of all traffic issues to be implemented i
Question: a) What is Client/Server and what benefits can be expected from Client/Server systems? b) Explain what middleware is and what it does. Why would MIS managers be p
Farmer Bob, Farmer Jane and Farmer Jose run a cow farming co-op. For every cow they keep the cow’s name, age (or date of birth), breed and numbered plastic ear tag. The each of t
can you please explain with the help of suitable example the difference between conflict equivalence and conflict serializability?
I am going to develop a web site to present decision tree structure. For this, I want a web application with AJAX technology to connect the database and prepare the decision tree's
Question: This question refers to the database schema. a) Express the following queries in SQL: (i) Write the SQL code that will create the table Company. Your answer sh
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd