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));
Rearrange Classes and Operations Sometimes, the similar operation is defined across different classes and can easily be inherited from a familiar ancestor, but more often oper
Define a view and a trigger. Construct a view for the above relations that have the information about suppliers and the elements they supply. The view holds the S#, SNAME, P# , PNA
What are the advantages of Logical Databases? It offers a simple-to-use selection screens. You can change the pre-generated selection screen to your needs. It offers check f
why older data models are being replaced by new data models.
What is the main advantage of the object model? What are its different components? The object model focuses on the logical data structures. Each object model comprises of many
Describe the advantage of State chart Diagram A state chart represents a state machine, emphasizing flow of control from one state to other. A state machine is a behaviour whi
1. Define each of the following IN YOUR OWN WORDS: (a) File: (b) Record: (c) Field: (d) Primary Key: (e) Secondary Key: 2. A travel agency wants t
domain
DROP TABLE Command: When an existing object is not needed for further use, it is always better to eliminate it from the database. To remove the existing object from the databas
1) Define a job scheduling strategy that will meet business requirement of reporting availability by 6am CST for the following cubes? Show the job scheduling dependencies in a pict
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