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));
What is meant by heuristic optimisation?Discuss the major heuristics that are applied during query optimisation.
Why does a DBMS query language is designed? A DBMS query language is designed to support end users who use English-like commands. support in the development of complex applicat
Types of data independence Data independence can be classified into the following two types: Physical Data Independence: This means that for any change made in the physi
a. Construct a query around any one of the functional divisions you made in 4a such that if executed in the distributed design of 4 would require reconstruction of at least two ho
Define the Boyce-Codd Normal Form with instance and also Compare BCNF and 3NF. Ans: BCNF: For each functional dependency X->Y in a set F of functional dependencies over relati
Consider employee (e_no, e_name, e_salary, d_code), dept (d_code, d_name) and dependent (depndt_name, e_no, relation). Show the names of employees in purchase and accounts departm
What are the object-oriented approaches Software systems which are designed with structured design methodology never support some of desired quality attributes for example reus
why shadow copy technique is used?
Why, generally does an object-oriented system use the relational DBMS? The reasons for using relational DBMS for OO systems could be any combination of following: a. Many or
what is un ordered and ordered file managment?
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