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#Data independence in dbms with example pdf form code

The First normal form simply says that each cell of a table should contain exactly one value. Each normal form has an importance which helps in optimizing the database to save storage and to reduce redundancies. There are various database “Normal” forms. The above is a simplified example of how database normalization works. In such a situation, replicating so much data will increase the storage requirement unnecessarily. However, think about the case when there are hundreds of courses and instructors and for each instructor, we have to store not just the mobile number, but also other details like office address, email address, specialization, availability, etc.

This may not be obvious in the above simple example. This avoids the stale/wrong data problem.įurther, if you observe, the mobile number now need not be stored 2 times. George, it can be done in exactly one place. Also, if we were to change the mobile number of Prof. Now, if someone wants to know the mobile number of the instructor, he/she can simply look up the instructor table. We rather store the ID of the instructor. What if someone just edited the mobile number against CS101, but forgot to edit it for CS154? This will lead to stale/wrong information in the database.īasically, we store the instructors separately and in the course table, we do not store the entire data of the instructor. In such a situation, we will have to make edits in 2 places. However, issues start to develop once we need to modify information. Here, the data basically stores the course code, course venue, instructor name, and instructor’s phone number.

#Data independence in dbms with example pdf form code

Here is what a sample database could look like: Course code

To understand (DBMS)normalization in the database with example tables, let's assume that we are supposed to store the details of courses and instructors in a university. For a better understanding of what we just said, here is a simple DBMS Normalization example: The core idea of database normalization is to divide the tables into smaller subtables and store pointers to data rather than replicating it.

Avoiding unnecessary data conflicts that may creep in because of multiple copies of the same data getting stored.ĭatabase Normalization is a technique that helps in designing the schema of the database in an optimal manner so as to ensure the above points.

Reducing the amount of storage needed to store the data.

Li-Yan Yuan for their notes.When developing the schema of a relational database, one of the most important aspects to be taken into account is to ensure that the duplication is minimized.

Join Strategies for Parallel Processors.

Estimation of Access Costs Using Indices.

Storage Structures for Object-Oriented Databases (Omitted).

RAID: Redundant Arrays of Inexpensive Disks (Not covered).

Comparison of Object-Oriented and Object-Relational Databases.

The ODMG C++ Object Manipulation Language.

The ODMG C++ Object Definition Language.

Storage and Access of Persistent Objects.

Alternative Approaches to Database Design (not to be covered).

Domain-Key Normal Form (not to be covered).

Normalization Using Join Dependencies (not to be covered).

Normalization Using Multivalued Dependencies (not to be covered).

Normalization Using Functional Dependencies.

Closure of a Set of Functional Dependencies.

Converting Queries Easily Into Any Language.

Test for the Absence of Duplicate Tuples.

Formal Definition of Relational Algebra.

Summer 1998 Table of Contents Chapter 1: Introduction Database Systems and Structures - Table of Contents CMPT 354: Database Systems and Structures