Database an introduction

Database an Introduction

Anwarul Islam,

PhD

Librarian
Sher-e-Bangla Agricultural University, Dhaka
anwarpulak@gmail.com

Agenda
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What is a Database?
Difference between data and information
Purpose of a database system
How to select a database system
Database definitions
Database development: the first steps
Quality control issues
Data entry considerations

What is a Database?
A database is any organized collection of
data.
Examples:
– a telephone book
– T.V. Guide
– airline reservation system
– motor vehicle registration records
– papers in your filing cabinet
– files on your computer hard drive

Data vs. Information
• What is data?
– Data can be defined in
many ways. Information
science defines data as
unprocessed information.

• What is information?
– Information is data that have
been organized and
communicated in a coherent
and meaningful manner.
– Data is converted into
information, and information
is converted into knowledge.
– Knowledge; information
evaluated and organized so
that it can be used
purposefully.

Why do we need a database?
• Keep records of :
– Patrons
– Staff
– etc
• To keep a record of activities and interventions;
• Keep service records;
• Develop reports;
• Perform research
• Longitudinal tracking

Purpose of a database system

Is to transform
Data

Information

Knowledge

Action

Types of Database
• Non-relational databases
Non-relational databases place information in field categories that we create so
that information is available for sorting and disseminating the way we need it.
The data in a non-relational database, however, is limited to that program and
cannot be extracted and applied to a number of other software programs, or

other database files within a school or administrative system. The data
can only be "copied and pasted.“ Example: a spread sheet

• Relational databases
In relational databases, fields can be used in a number of ways (and
can be of variable length), provided that they are linked in tables. It is
developed based on a database model that provides for logical
connections among files (known as tables) by including identifying
data from one table in another table

Selecting a Database Management System
Database management systems (or DBMSs)
can be divided into two categories -- desktop
databases and server databases.
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Generally speaking, desktop databases are oriented toward
single-user applications and reside on standard personal
computers (hence the term desktop).

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Server databases contain mechanisms to ensure the reliability
and consistency of data and are geared toward multi-user
applications.

Database definition
An organized collection of data. A database
management system (DBMS) such as Access,
FileMaker, Lotus Notes, Oracle, SQL Server,
MySql which provides you with the software
tools you need to organize that data in a flexible
manner. It includes tools to add, modify or
delete data from the database, ask questions (or
queries) about the data stored in the database
and produce reports summarizing selected
contents.

Selecting a database system: Need Analysis
The needs analysis process will be specific to your organization
but, at a minimum, should answer the following questions:
• How many records we will warehouse and for how long?
• Who will be using the database and what tasks will they
perform?
• How often will the data be modified? Who will make these
modifications?
• Who will be providing IT support for the database?
• What hardware is available? Is there a budget for purchasing
additional hardware?
• Who will be responsible for maintaining the data?
• Will data access be offered over the Internet? If so, what
level of access should be supported?

Quality Control Considerations
• Remember “garbage in – garbage out”. Some
examples and how to prevent this.
• Quality management encompasses three
distinct processes: quality planning, quality
control, and quality improvement
• Quality Planning in relation to database systems
design:
– Who will perform data entry?
– Training? On-line help?
– How data entry will be performed?

• Barcode scanners
– USB or
– Wireless attached to a Palm or Pocket PC

• Pocket PC
– WiFi 802.11g, Bluetooth
– Wireless networks (real-time on demand
systems

• Define “must” enter fields – no record is
complete unless: such and such is
entered;
• Make data entry fool proof.
– By using a pull-down menu with the correct
data format these mistakes can be avoided.

Define some key Access
terminology
Field
– A single characteristic or attribute of a person,
place, object, event, or idea.
Record
– A set of related field values.
Table
– A collection of records that identify a category
of data, such as Customers, Orders, or
Inventory.

Illustration of fields, records and
a table

Relational database and keys
• A relational database is a collection of tables
that are related to one another based on a
common field.
• A field, or a collection of fields, is designated as
the primary key.
– The primary key uniquely identifies a record in the
table.

• When the primary key of one table is
represented in a second table to form a
relationship, it is called a foreign key.

Relating tables using a common
field

Open an existing database
• When Access is launched you will see the
Access window, with the task pane on the right
side
• From the task pane you can open an existing
database by:
– Selecting the database you want from the list of
Recently opened databases
– Selecting “Look in” list arrow to choose a database
you want to open from a storage location
• If you choose the Look in list arrow, you will browse to the
correct location of your database, click on it, and then click
on Open to open the database

The Database window
• The Database window is the main control
center for working with an Access
database.
• The Database window contains a menu
bar, an objects bar, and a groups bar.
– The Objects bar lists all the objects available
in the database
– The list of objects consists of tables, queries,
forms, reports, pages, macros, and modules
– You can click on any of the objects in the
Objects bar to obtain a list of objects of that
type

Use the task pane to open a
database

Selecting fields to include in a
query
• You can create a query that will display only selected
fields from a table instead of displaying all fields.
• In the Simple Query Wizard dialog box, select which
fields you want included in the query.
– Move all the fields into the Selected Fields box
– Move the fields one at a time
– Remove fields out of the Selected Fields box by pressing one of
the remove buttons

• If you wanted to select all the fields except one, you can
move them all to the selected fields list and then remove
the one field you don't want.
• Once you have made your selections, press Next to
move to the next dialog box in the Wizard.

Create an Access form
• A form allows you to view your data one
record at a time.
• Forms are useful for maintaining, viewing,
and printing records in a database.
• You can create your own form in the
Forms Design window or you can use the
Forms Wizard to create a form.
• The easiest way to create a form is to use
the AutoForm Wizard.

Use the AutoForm Wizard
• The AutoForm Wizard uses a table (or query)
you select as the basis to create a form that
displays all the fields of the table (or query).
• Once you have created your form, you can view
the records one record at a time.
• The form has a navigation bar just like the
navigation bar you have already used in the
Table or Query Datasheet view.

Create, preview, and navigate a
report
• You can create a report, which is a printed
version of your data, that is formatted
according to your specifications.
• The data in the report can consist of data from
a single table or multiple tables.
• Access has a Reports Wizard that allows you
to easily create a report.
• The report can be based on a table or it can be
based on a query.
– If the report is based on a query, it will contain the
same fields that were selected for the query

Database an introduction

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