Database Design Lecture 1 Introduction to Databases and DBMS

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Database Design Lecture 1 Introduction to
Databases and DBMS

• Dr. Dhiya Al-Jumeily
• d.aljumeily_at_livjm.ac.uk
• Room 630

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Lecture objectives

• In this lecture we will learn about
• The evolution from file-based storage to DBMS.
• The meaning of the term Database and Database
  Management System (DBMS).
• The separation of data definition from
  applications.
• The development of data models over time and its
  terminology.

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Conventional File-Based System
Management
?
Sales
Purchasing
Production
Stock Control
Delivery
Account
Separate Systems For Separate Functions
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The Limitation of the File-Based Approach

• Duplication of Data.
• Separation and Isolation of Data.
• Data Dependence.
• Incompatible file Formats.

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The Database Management System (DBMS)

• DBMS Provides ways to
• Define the structure of the data.
• Manipulate data values within the database.
• Control access to the data, for example
• a security system.
• an integrity system.
• a concurrency control system.
• a recovery control system.

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The DBMS Approach
Different Applications
Sales
Database
DBMS
Accounts
Research
Data held in one central system
Different users access the system through DBMS
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Query Language
Sales
Users Programs
Accounts
Database
DBMS
Research
Query Language
The Manipulation of data done usually using Data
Manipulation Language (DML), which provides a
general enquiry facility to the database, called
QL
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Databases

• Database is essentially a means of storage and
  retrieval of items of data. The data is usually
  either numerical or textual, although other data
  forms can be accommodated. Database can refers
  to
• Database packages
• (Informix, dBase IV, Ingress, Access,
  Oracle,....).
• Application database
• ((Our Main Concern)).
• Many PC/.. database packages have limited DBMS
  facilities.

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Relational Data Model

• It was first developed by E.F.Codd in the early
  1970s as an approach to find and control
  information away from the user and provide an
  interface which would accept simple appropriate
  commands to find whatever was needed
• Examines the problem area to identify the data
  needed and its use.
• Works towards building a formal conceptual data
  model
• Shows types of data relationships between types.

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Database Design

• Conceptual Model
• Models problem data independent of DBMS
• Logical Model
• Defines structure of data for DBMS (Schema)
• Physical Model
• Physical file structures generated from schema

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Database Administrator (DBA)

• The DBA has overall responsibility for the
• database, including
• Planning.
• Development and maintenance of standards.
• Polices and procedures.
• Conceptual and logical database design.

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CASE Tools for database Design

• Tools that can provide support for the main
  phases of the development of a database
  (Conceptual, Logical and Physical)
• Some basic features
• Graphical Interface Manipulate E-R diagrams
• A data dictionary Store information on various
  components
• Integrated tools Carry out specific design tasks

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Summary of the Lecture

• DBMS is now the underling frame of the
  information system and has fundamentally changed
  the way organisation operate.
• The database approach emerged to resolve the
  problems with the file-based approach. A database
  is a shared collection of logically related data,
  design to meet the information needs of an
  organisation.
• A data model is a collection of concepts that can
  be used to describe a set of data, the operations
  to manipulate the data, and a set of integrity
  rules for the data.
• Conceptual modelling is the process of
  constructing a detailed architecture for a
  database that is independent of implementation
  details.