BTM 382 Database Management

Chapter 1: Database systems

Chitu OkoliAssociate Professor in Business Technology Management

John Molson School of Business, Concordia University, Montréal

Why do we need databases?

Structural and Datadependence and independence

Structural dependence and independence Structural dependence: Access to a database file is dependent

on the precise database structure E.g. if you add a new field (attribute), you have to modify all

application programs that access the database Structural independence: File structure can be changed without

affecting applications’ ability to access the data Data dependence and independence

Data dependence: Access to a database file is dependent on the precise format of the data E.g. if you change the number of decimal places for a numeric field,

you have to modify all application programs that access that field Data independence: Data storage characteristics can be

changed without affecting applications’ ability to access the data

Data redundancy

Unnecessarily storing the same data at different places in the database

Problems: Poor data security Data inconsistency Increased likelihood of data-entry errors when

complex entries are made in different files Data anomaly: when not all of the required changes

in the redundant data are made successfully

Database and DBMS

A database is a shared, integrated computer structure that stores a collection of: End-user data - Raw facts of interest to end user Metadata: Data about data, which the end-user data are

integrated and managed Describe data characteristics and relationships

Database management system (DBMS) Collection of programs Manages the database structure Controls access to data stored in the database

The DBMS manages the interaction between the end user and the database

Databases versus file systems

Types of databases

Types of databases:

Number of users Single-user database: Supports one user at a time

Desktop database: Runs on PC Multiuser database: Supports multiple users at the

same time Workgroup databases: Supports a small number of

users or a specific department Enterprise database: Supports many users across many

departments

Types of databases:

Physical location Centralized database: Data is located at a single site Distributed database: Data is distributed across

different sites Cloud database: Created and maintained using cloud

data services that provide defined performance measures for the database

Types of databases:

Operations versus analysis

Operational database: Designed to support a company’s day-to-day operations

Analytical database: Stores historical data and business metrics used exclusively for tactical or strategic decision making Optimized for read-only operations; very slow for

updating Data warehouse: Stores data in a format

optimized for decision support

Types of databases (correction/clarification):

Information provision databases All the other kinds of database described are

fully functional databases where the users can read, write and edit data

Unlike the other kinds of database described, General-purpose databases and discipline-specific databases refer to prepopulated read-only databases provided for information purposes by specific vendors

Database management

The database system environment

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Structure of BTM 382Database Management Week 1: Introduction and overview Weeks 2-6: Database design Week 7: Midterm exam Weeks 8-10: Database programming Weeks 11-13: Database management

Sources

Most of the slides are adapted from Database Systems: Design, Implementation and Management by Carlos Coronel and Steven Morris. 11th edition (2015) published by Cengage Learning. ISBN 13: 978-1-285-19614-5

Other sources are noted on the slides themselves

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