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));
For the relations answer the following queries in SQL Street (name, location, city) House (number, street_name) Lives (name, house_number) (i) Obtain the names of persons who liv
Sequential File Organisation The most necessary way to organise the collection of records in a file is to use sequential Organisation. Records of the file are stored in series
Explain Data Sublangauges ? Data sublanguage: In relational database theory, the term sublanguage, first used for this purpose through E. F. Codd in the year of 1970, refers t
Define instance and schema? Instance: Collection of data kept in the data base at a particular moment is known as an Instance of the database. Schema: The o
What are the states of transaction? The states of transaction are:- a) Active b) Partially committed c) Failed d) Aborted e )Committed f) Terminated
what characterizes the levels in RAID technology
Order by clause By using this rows can be sorted It is used in the last portion of select statement By default it gets ascending order DESC: is used
The issues relating to the Design of the Physical Database Files Physical File is a file as stored on the disk. The major issues relating to physical files are: • Cons
What is Distributed system ? Distributed System - A distributed system consists of a number of processing parts in which are interconnected through a computer network and in
Using the questions found at the end of Chapter 9 in your textbook, complete this homework activity. Students will submit a Word document answering questions 2, 3, and 4.
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