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));
Hi I have got an assignment for making an er diagram for market management software can any budy help me?
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
Define an abstraction by which relationships are treated as higher level entities Ans: Aggregation. It is an abstraction by which relationships are treated as higher level
Consider the subsequent relations along with keys underlined Street (name, location, city) House (number, street_name) Lives (name, house_number) Define the above relations
describe objectivde of file organisation
Differentiate between join and outer join? Outer joins return all rows from at least one of the tables or views mentioned within the FROM clause, as long as those rows get toge
find the name of supplier who supply some red part
Whta is the advantage of the database management approach? The advantage of the database management approach is data is integrated and can be accessed by multiple programs.
what is stracture of dabms
One-way Associations If an association is only traversed in single direction, then it is known as one-way association. It is implemented as a pointer or an attribute which con
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