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));
Table_Name( attribute_1, attribute_2, attribute_3, ….. ,attribute_x) Primary Key ( attribute_1, attribute_2) Foreign Key attribute_4 References Table_Name_2 (repeat for each fore
Explain Candidate Key and Super Key A super key is a set of one or more than attributes that, taken collectively, permits us to identify uniquely a tuple in the relation. Wher
What are metrics for choosing the best algorithm? Matrices for choosing the best algorithms are as below: Computational complexity Ease of understand ability and im
The Internal or Physical Level The collection of files permanently stored on secondary storage devices is called as the physical database. The internal or physical level is t
Create centralized relational database using Top down method- Construction of Logical Model: Translation EERD into Relational Schema: Use the 8 steps algorithm of converting EERD
Hierarchical
Explain what is Aggregation ? Aggregation: This is used whenever we intend to show a relationship between an entity and the relationship. There is no provision for this in th
What are the two types of indices? The two types of indices are:- A) Dense index B) Sparse index
Need a sample of a clinic database relationships
In order to keep pace with competitors, Space Ltd has decided to implement an ERP system in order to replace its old legacy and manual systems. Management does not have much knowle
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