Datab ase Systems Week 1 by Zohaib Jan

About the course

About the course Ref Text Book: Fundamentals of Database Systems 6th Edition by PEARSON PUBLISHERS

What is a data base ? A database is a collection of related data. What is Data ? Collection of records that have known meaning and are either facts or figures or have some meaning (ie Information)

What is DBMS Database Management System is collection of programs that enable users to maintain and create databases. The DBMS is a general-purpose software systemthat facilitates the processes of defining, constructing, manipulating, and sharing databases among various users and applications

DBMS Defines Creates Manipulates

DBMS Provides Efficient, Reliable, Convenient, Safe, Multi User, Storage to MASSIVE amounts of PERSISTENT data What’s missing ?

DBMS Access ? How do you access data ?

What is most important to DBMS

DBMS

DBMS DBMS may be developed by using Frameworks… DBMS may be used with Middlewares Lastly may not be dependent on DBMS at all

Data Model How is your data stored ? Can be in forms of records Can be in form of XML / JSON Can be in form of Graph

Schema Structure of the Data and Data Base Data will adhere to the Schema Schema doesn’t change over time data does

DDL Data Definition Language Is used to define the schema

DML Data Manipulation Language The language used to interact with your data

DBMS users Database Administrator Database Designer Database Application Developer Database Implementer

Advantages of USING DBMS Controlling redundancy Restricting Unauthorized Access Providing Persistent Providing Storage Structures and Search Techniques for Efficient Query Processing Storage for Program Objects Providing Backup and Recovery Providing Multiple User Interfaces Representing Complex Relationships among Data Enforcing Integrity Constraints

Further Reading Chapter 1 of reference book

Data Model A data model—a collection of concepts that can be used to describe the structure of a database

Categories of Data Model High level or Conceptual data models – concept of data Physical or low level models – how data is stored

High level / Conceptual data models Entities Attributes Relationships

Entities An entity represents a real-world object or concept, such as an employee or a project

Attributes An attribute represents some property of interest that further describes an entity, such as the employee’s name or salary.

Relationship A relationship among two or more entities represents an association among the entities, for example, a works-on relationship between an employee and a project

Entity Relationship Model A high level conceptual data model

Relational Data Model How data is represented in the DBMS SQL

Object Data Model A standard for object databases called the ODMG object model has been proposed by the Object Data Management Group (ODMG)

Schema

Three schema architecture The internal level schema The conceptual level schema The view level schema

Data independence The capacity to change the schema at one level of a database system without having to change the schema at the next higher level 2 types of data independence Logical data independence is the capacity to change the conceptual schema without having to change external schemas or application programs Physical data independence is the capacity to change the internal schema without having to change the conceptual schema. Hence, the external schemas need not be changed as well

Further Reading Chapter 2 of reference book