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));
Winfield is a small city with a population of 22,000 with buses serves three routes in Winfield and neighboring areas. As the city’s IT director, you have been asked to set up an i
Increased overheads on update : On the drawbacks side, it will need the system to ensure that all replicas of a relation are consistent. This shows that all the replicas of the rel
The Third Normal Form (3NF) Even though, transforming a relation that is not in 2NF into a number of relations that are in 2NF take out many of the anomalies, it does not neces
A database is to be constructed to remain track of the teams and games of a sport league. A team has a number of players, not all of whom participate in every game. It is desired
Physical Records These are the records that are stored in the secondary storage devices. For the database relation, physical records are the group of fields kept in adjacent me
Consider the table student and list names of students in the departments other than maths and computer. SELECT std_name FRM student WHERE dept_name NOT IN (‘Maths','Computer);
Explain controlled redundancy? Controlled redundancy : The replication of data within the data warehouse for the purposes of improved data access or understand ability.
A use case diagram giving a pictorial overview of user requirements and brief use case descriptions. As the case study contains only an outline of a business scenario, you will als
Which of the operations constitute a basic set of operations for manipulating relational data? Relational algebra operations constitute a basic set of operations for manipulati
What does the extract statement do in extract datasets? The data is written to virtual memory by extract commands.
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