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));
Q. Why would you choose a database system instead of simply storing data in operating system file? Define at a base concept in details. Sol. Advantages of Database over Fil
Describe Object Relational model ? Object Relational Model - This model combines the characteristics of both relational model and object oriented model. It extends the tradit
With the help of a suitable diagram gives module wise explanation of system architecture of DBMS.on..
What is serialization? Where it is used and why? Serialization is a basic term used for mechanisms which enable objects and object structures to be converted into portable for
can you create a database for me in oracle/sql
What are ways of finding out either an update is required or not for derived attributes? The ways to find out an update is required or, not are as: Explicit update
What is the need of a log in a DBMS? Briefly describe the various types of records that are normally present in a log. Ans: The system log, which is generally writt
Q. Describe how an ER schema can be represented by relation schemas and constraints arising from ER design can be mapped to constraints on a relation schema. The entity rela
The Locking Protocol: To manage concurrency related problems we use locking. A lock is mainly a variable that is associated with a data item in the database. A lock can be located
What is D command work in the respect of QBE? D: It is the command inside QBE to delete tuple(s) from the relation.
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