IST 220 - Intro to DBLecture 1

What is Database?

What Is a Database?

To answer this question, we will discuss the following related concepts Data Information Database Relational database Database management system Database applications

Data

Definition by Merriam-Webster’s factual information (as measurements or statistics)

used as a basis for reasoning, discussion, or calculation

Raw data Raw data (pieces of information) may not be so

helpful without proper manipulation Data is the set of original value you store in the tables of the database

You store data. You define (the structure of) your data.

Information

Information is Derived from raw data Specially prepared for a certain audience

Before useful information can be obtained Data needs to be defined and stored in a highly

organized manner Data should be easy to add into and retrieve from a

database Information is data that is retrieved and organized in a way that is meaningful to the person viewing it.

You retrieve, process & present information

Database A database is a collection of related raw data

that is well-defined and organized.

Aug 13 Adah Talbot ½ day in the afternoon$0.50

Banked for Hara Talbot

A 100-Year-Old Example

Relational Database

Backed by sound mathematical theories, RDBs provide a better way to organize user data Usually with data for several subjects (entities) within a

certain application (domain) Teams Players Games Scores and technical statistics

In a relational database, data are stored in tables each of which is designated for a specific subject The mathematical term “relation” defines a data structure for

which a table is the exact incarnation

Example of a Table – Hawks Roster

Hawks Roster

  2002-03 Roster

 NUM PLAYER POS HT WT DOB FROM YRS

 3 Shareef Abdur-Rahim

F 6-9 230 12/11/76 California '99 6

  David Andersen F 7-0 242 6/23/80 Australia R

 6 Cal Bowdler (FA) F 6-10 253 3/31/77 Old Dominion '99 3

 4 Chris Crawford F 6-9 235 5/13/75 Marquette '97 5

 15 Emanual Davis G 6-5 195 8/27/68 Delaware State '91 5

 12 Dan Dickau G 6-0 190 9/16/78 Gonzaga '02 R

 5 Dion Glover G 6-5 228 10/22/78 Georgia Tech '02 3

 44 Alan Henderson F-C 6-9 240 12/02/72 Indiana '95 7

 1 DerMarr Johnson F 6-9 201 5/05/80 Cincinnati '03 2

 2 Nazr Mohammed C 6-10 250 9/05/77 Kentucky '99 4

 14 Ira Newble (FA) F 6-7 215 1/20/75 Miami (Ohio) '97 2

 42 Theo Ratliff C-F 6-10 230 4/17/73 Wyoming '95 7

 13 Glenn Robinson F 6-7 230 1/10/73 Purdue '94 8

 30 Mark Strickland (FA) F 6-10 220 7/14/70 Temple '92 7

 31 Jason Terry G 6-2 176 9/15/77 Arizona '99 3

Row (orrecord)

Column (or field)

Database Management System

• A DBMS is a software system which takes care of Data definition Data storage and retrieval Data manipulation

Insertion Modification Deletion

Other functions, such as security, transaction control, archiving, backup and recovery

By using a DBMS, applications programmer can focus on business logic

CRUD - Create (or insert)- Retrieve (or search)- Update- Delete

File-Processing Systems

X

File-Processing Systems

Records are stored in separate files Drawbacks

Separated and isolated data Data duplication Application program dependency

Read from the product file for 20 bytes starting from location 1234, from the customer file ...

The difficulty of synchronize data changes The difficulty of representing data in the users’

perspectives

Why DBMS?

Database Systems

DB technology was developed largely to overcome the limitations of file systems

Advantages Integrated data Reduced data duplication Program/data independence, through the use of SQL

SELECT ProductName FROM Product WHERE ProductId = ‘P010’

Easier to update Easier representation of the users’ views

Relational Databases

The term relational is used because In RDB, data are stored in tables. Each table is a mathematical relation on a number

of sets

Related tables are linked with shared columns

Aug 13 Adah Talbot ½ day in the afternoon$0.50

Month {Jan, …, Dec}Day {1, 2, …, 31}Worker {…}Time worked {…}Wage {…}

RDBMS Capabilities

Data definition Attributes – columns of your tables Data types – date, text, numeric, money, etc Relationships – among data in different tables

Data manipulation Data control – permission to use data

Fans can read statistics on website The Hawks manager can add, remove, and modify

player records

Data Definition

A database is self-describing Metadata – data used to define user data

or data about data

Aug 13 Adah Talbot ½ day in the afternoon$0.50

MonthDayWorkerTime workedWage

Text Number Text Text Money

Metadata, or schemaUser data

Data type Valid range

{Jan, …, Dec}{1, 2, …, 31}{…}{…}{…}

Field name

Example – Data Definition in Access

Example – Relationship in Access

Components of DB Systems

DB Users

Types of Users End users (naïve users)

Limited access to data, through forms or reports Application developers

Use programming languages w/ DB accessibility Sophisticated users

Use query languages and tools Specialized users

Write special applications, such as CAD, GIS, etc

DB Administrators

DBA is the central control over the system DBA functions include

Schema definition and modification Storage structure definition Granting authorization for data access

Read only Change (add and/or modify) Create tables and modify schema

Routine operation and maintenance

When to Use a DBMS?

A significant amount of related data Data about different subjects Multiple uses of these data

Data used by multiple users Changes to data should be synchronized Accesses to data must be controlled

Sample DB Applications

In a local area network

Sample DB Applications

In a wide area network or over the Internet

Characteristics of Types of DBs

Type Sample Application

Number of Concurrent users

Typical Size of Database

Personal Wedding list 1 < 10 MB

Small Business

Entertainment scheduling

<25 < 100 MB

Organizational Licensing and registration

Hundreds > 1 trillion bytes

Internet Microsoft Press Books

Possibly Hundreds

Any