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					Lectures
CS2008 Data Management CS5035 Introduction to Database Systems
Yaji Sripada yaji.sripada@abdn.ac.uk www.csd.abdn.ac.uk/~ssripada
• CS2008+CS5035
– Two lectures per week in New King’s 10 – @ 15:00 Hours on Tuesdays & Fridays

• Course Duration
– 12 weeks

• 23 lectures + 1 revision
– In the revision class we go through previous years’ exam papers

• Textbook
– Database Systems by Connolly & Begg (Fourth Edition) – I refer to it as C&B
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Practicals
• CS2008
– One practical per week in Fraser Noble 116
• Mon 13-15 • Lectures
– 4 Parts

Course Overview
• Practicals
– 3 Groups – Separated by 3 Assignment practicals

• Part 1
– Relational Model & SQL

• CS5035
– One practical per week in MacRobert 117
• Thu 15-17

• • • • • •

Group 1
– MSAccess and SQL

• Part 2
– Database Analysis & Design, ER Models, Methodology

Assignment Practical 1 Group 2
– Database Design & ER Models

• Part 3
– Database Application Development using Java and PHP

Assignment Practical 2 Group 3
– Database Connectivity

Assignment Practical 3

• Part 4
– DBMS Internals
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Assessment
• One 2-hour exam in January (75%) • Assignments (25%)
– 2 for CS2008 – 1 for CS5035

Introduction
Reading: C&B, Chap 1

• Overall pass and exam pass needed

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In this lecture you will learn
• • • • What is a database? File based systems & their disadvantages Components of the DBMS environment Advantages & disadvantages (?) of using DBMS

The Big Idea -I
• Consider a heap of coloured balls • No organization • No structured search possible for a specific coloured ball • Search inefficient • Note: Focus is on search/retrieval

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The Big Idea - II
• Faster search possible by dividing the heap • Search fails to exploit the natural structure in the heap

The Big Idea - III
• Balls organized into different colours • Natural structure exploited • Structured search possible
– Search also efficient

BIG IDEA ---- Organizing data based on the natural structure of the data for efficient search
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What is a database?
• Initial definition
– A collection of related data. – (Not a collection of raw data) • Universities

Why bother?
• Libraries (Digital?)
– Aberdeen University Library Catalogue – Student Record System of Aberdeen University

• We return to this definition many times during the course • We may add details to the initial definition • At the end of teaching,
– you give your own definition
• May be with more details
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Flight & Holiday Booking DNA & Genomics GIS ….. …… All major domains of human activity use database technology!!! • Hard to imagine modern world without database technology
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• • • • • •

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Need for Organizing Data
• In all the above examples, data needs to be organized (structured)
– Organization brings order from chaos

What is a database? (2)
• Database (DB)
– Collection/Repository of related data – E.g. DreamHome2.mdb

• Organization of data helps in accessing specific data items efficiently
– Accessing data items from unorganized data is inefficient – Imagine searching for a specific book in a library with one large stack of all the books in the library

• Database Management System (DBMS)
– Software that manages and controls access to the database – E.g. MSAcess

• Database Application (DA)
– A program that interacts with the database at some point in its execution – Using a query language (SQL) – E.g. A Java or Php application on DreamHome database

• Databases are organized collection of related data!
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• Database system
– DAs+DBMS+DB
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Example Database Management Software
• MSAccess – we use in this course • MySQL – freeware (Windows & Unix) – we use in this course • McKoi – freeware, Java based • Oracle • SQL Server – Microsoft database server • ….

File Based Systems
• Data stored in files • Application programs work directly on files • Data defined separately in each program • Data processing (manipulation) takes place separately in each program • Data redundant across files
Program 1 Data Definition 1 Data Manipulation 1 Program 2 Data Definition 2 Data Manipulation 2 Program 3 Data Definition 3 Data Manipulation 3

File 1

File 2

File 3

Redundant data

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Disadvantages of File-based Systems
Program 1 Data Definition 1 Data Manipulation 1 Program 2 Data Definition 2 Data Manipulation 2 Program 3 Data Definition 3 Data Manipulation 3

Top Requirements
• Data to be structured, defined and stored independent of application programs
– Data + metadata = database (another definition!)

File 1

File 2

File 3

Redundant data

Result:

• Data Separation & isolation • Data duplication • Data dependence • Incompatible file formats • Fixed queries & proliferation of application programs

• Access and manipulation of data possible only through a common interface to all application programs
– DBMS offers the common interface

•Unhappy end-users and unhappy developers!!! •Unhappy system maintenance Staff.
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What is a database? (3)
• Database (DB)
– Shared collection of logically related data and a description of this data

Components of the DBMS environment
Data Hardware Software Machine Bridge Procedures People Human

• Database Management System (DBMS)
– Software that enables users to define, create, maintain and control access to the database

• Hardware
– Single PC – A single mainframe – Server-client Model

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Components of the DBMS environment (2)
• Software
– DBMS – Network software – Programming languages

Components of the DBMS environment (3)
• Procedures
– Log on to DBMS – Start & Stop DBMS

• People (Jobs for you?)
– – – – Data & database administrators Database designers Application developers End-users

• Data
– Operational data – Metadata – System catalog

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Advantages of databases
• • • • • • • Control of data redundancy Data consistency Improved security Increased concurrency Enforcement of standards Improved backup and recovery More in C&B section 1.6 • • • • •

Disadvantages
Complexity Size Higher impact of a failure More in C&B section 1.6 Simple applications may not need DBMS at all
– Apply common sense!

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Conclusion
• Database - valuable shared resource in an organization • Advantages in using DBMS in an application outweigh disadvantages • Database study involves
– Designing databases + using them in applications – Generic functionality of the DBMS

• Learn concepts in relation to a real DBMS, say MSAccess. • MSAccess stores database in files but offers tables to users • How is this done? – Relational Model
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