Terms:

1
INTRODUCTION

• Terms
• Data
• Data is defined as a collection of facts and
  figures that can be recorded and has implicit
  meaning.
• Database
• Database is a collection of related data.
• Database Management System
• DBMS is a collection of programs that enables
  users to create and maintain a database.

2

• Properties of Database
• A database represents some aspects of the real
  world.
• A database is a logically coherent collection of
  data with some inherent meaning.
• A random assortment of data cannot be termed as
  database.
• A database is designed, built and populated with
  data for a specific purpose. It has an intended
  group of users and preconceived applications in
  which these users are interested.

3

• Types of Databases
• Traditional Database
• Textual or numeric in nature.
• Geographic Information System
• Maps, weather data, satellite images.
• Multimedia Database
• Pictures, video clips, sound messages.
• Data Warehouses and Online Analytical Processing
• Integration of data and for decision making.
• Real Time and Active Database
• Controlling industrial and manufacturing
  processes.

4

• Database Applications
• Banking all transactions
• Airlines reservations, schedules
• Universities registration, grades
• Sales customers, products, purchases
• Online retailers order tracking, customized
  recommendations
• Manufacturing production, inventory, orders,
  supply chain
• Human resources employee records, salaries, tax
  deductions
• Databases touch all aspects of our lives.

5

• Database Management System
• DBMS consists of
• Collection of interrelated data
• Set of programs to access the data
• The main goal is to provide an environment that
  is both convenient and efficient to use.
• DBMS provides for
• Definition of structure for the storage of data.
• Provision of mechanisms for manipulating
  information.
• Safety of information in case of system crash or
  unauthorized access.
• Concurrency control in case of multi user
  environment.

6

• DBMS facilitates for
• Defining a database
• Constructing a database
• Manipulating a database.

7

• Purpose of Database Systems
• In the early days, database applications were
  built directly on top of file systems.
• What is a File System?
• In file system permanent records are stored in
  various files and different application programs
  are written to extract records from, and to add
  records to, the appropriate files.

8

• Drawbacks of using file systems to store data
• 1. Data redundancy and inconsistency
• Multiple file formats,
• Programs in multiple programming languages,
• duplication of information in different files,
• data inconsistencies.
• 2. Difficulty in accessing data
• Need to write a new program to carry out each new
  task
• 3. Data isolation
• Data scattered in multiple files.
• multiple files and formats
• Difficult to write new application program to
  retrieve data.
• 4. Integrity problems
• Consistency Constraints
• Integrity constraints (e.g. account balance
  gt1000) become buried in program code rather
  than being stated explicitly
• Hard to add new constraints or change existing
  ones

9

• 4. Atomicity of updates
• Failures may leave database in an inconsistent
  state with partial updates carried out.
• Example Transfer of funds from one account to
  another should either complete or not happen at
  all.
• Difficult to ensure this property in file system.
• 5. Concurrent access by multiple users
• Concurrent access needed for performance.
• Uncontrolled concurrent accesses can lead to
  inconsistencies.
• Example Two people reading a balance and
  updating it at the same time.
• 6. Security problems
• Hard to provide user access to some, but not
  all, data Database systems offer solutions to all
  the above problems.

10

• Main Characteristics of Database Technology
• Self-contained nature of a database system
• A DBMS catalog stores the description of the
  database. The description is called meta-data).
  This allows the DBMS software to work with
  different databases.
• Insulation between programs and data
• This is called program-data independence.
  Allows changing data storage structures and
  operations without having to change the DBMS
  access programs.

11

• 3. Data Abstraction
• A data model is used to hide storage details
  and present the users with a conceptual view of
  the database.
• 4. Support of multiple views of the data
• Each user may see a different view of the
  database, which describes only the data of
  interest to that user.
• 5. Sharing of data
• 6. Multi-user transaction Processing.

12

• Additional Benefits of Database Technology
• Controlling redundancy in data storage.
• - Sharing of data among multiple users.
• - Restricting unauthorized access to data.
• - Providing multiple interfaces to different
  classes of users.
• - Representing complex relationships among data.
• - Enforcing integrity constraints on the
  database.
• - Providing backup and recovery services.
• - Potential for enforcing standards.
• - Flexibility to change data structures.
• - Reduced application development time.
• Availability of up-to-date information.
• Economies of scale.

13

• Users of Database
• Database Administrators
• authorizing access to database,
• Coordinating monitoring database use,
• Acquiring software hardware resources as
  needed,
• Accountable for breach of security or poor system
  response time.
• 2. Database Designers
• Identify data to be stored in db,
• Select appropriate structure for storing data,
• Communicate with all users and understand their
  requirements,
• Design a database that meets user requirements.

14

• 3. End Users
• Casual End Users
• Occasionally access a db,
• Needs different information each time,
• Use sophisticated database query language.
• E.g. middle or high level managers.
• Naïve or Parametric End Users
• Constantly query and update the database,
• E.g. Bank tellers, Railway reservation clerks
  etc.
• Sophisticated End Users
• Users who use database to meet complex
  requirements.
• E.g. Engineers, scientists, business analysts.
• Stand alone Users
• Use readymade program package to interact with
  database.

15

• 4. System Analyst Application Programmers
• System analyst determine the requirements of end
  users
• Application programmers implement these
  specifications as programs.
• Both are called software engineers.
• 5. Operators Maintenance Personnel
• Responsible for the actual running and
  maintenance of H/W S/W environment for the
  database system.