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));
" Wound-wait" scheme : It is based on a preemptive method. It is based on a simple rule: If Ti requests a database resource that is held by Tj
prototype of a distributed information system for a national car part retail outlet chain.
Should I select imaging software that allows changes? An imaging system should not give features to edit or alter images. Images generally are formed as safe and secure records
The PROJECT operation The project operation is used to choose the records with specified attributes as discarding the others based on some related criteria. This is denotes as ∏
List and also explain the dissimilar stages of DDLC ?
Give short note on the following terms:Dirty pages and ETL a.) Dirty pages. These are buffer pages which comprise modifications which haven't been written to disk. b.
Explain the disadvantages of file oriented approach? In the oriented approach Applications are designed in isolation. Design of application is optimized for one application. In
projects?
What is the difference between internal tables and extract datasets? The lines of an internal table always have the similar structure. By using extract datasets, you can ha
What is a virtual table that draws its data from the result of an SQL SELECT statement? View is a virtual table that draws its data from the result of an SQL SELECT statement.
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