Download DATABASE

DATABASE
What is a database ?
• Database is an organized collection of
structured data.
• Database can be used to store information of
students in school, about vehicle
registrations, stock in supermarket, books in
library..etc.
Examples of database
1. Microsoft Access 2010
2. Open Office programs like Calc and Writer.
types of Database
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Flat file database will have one table in
database file.
Relational database will have two or more
tables that are linked in a database file.
Creating a database
To create a database in access:
1. Select new from office button menu.
2. Click on blank database
3. Select a location to store the database
4. Give filename
5. Click on create
Objects
Database objects available are listed at the lefthand side of the database window.
Continued
Tables, forms, queries, report and other objects
in a database can make it easier to perform a
wide variety of tasks- such as entering data
into a form, adding or removing tables, finding
and replacing data, and running queries.
Continued
Table: a collection of related data about a
subject (person, place, thing). It is divided into
rows and columns.
Query: are used to search and extract
information in a database. After you run a
query, a group of records are displayed in a
table that satisfies or answers the query.
Report: is an attractive display on the monitor
screen or printout of information in a table.
Designing a database
a) Determine the purpose of the database
b) Analyze each purpose
c) Determine the data you need to meet the
purpose.
d) Design your tables
e) State the field names and its data type
f) Determine how the table will be related
Tables
Table an organized collection of related records
about a subject (person, place, thing). It is
divided into rows and columns.
FIELDS
Primary key
• A Primary Key is often referred to as Key field.
• Primary Key is a field used to uniquely
identify each record in a database. Eg.
Itemcode, Customerno, Registrationno..etc.
Advantages of primary key
• It can speed up retrieval of data and running
of queries.
• It enables you to link tables in a database
Steps involved in designing a database
• Determine the purpose of the database
• Analyze each purpose
• Determine the data you need to meet the
purpose.
• Design your tables
• State the field names and its data type
• Determine how the table will be related
Methods used in MS Access to create a
Table
• Design View: This method enables you to
create table by naming the fields, selecting
their data types.
• Datasheet view: You enter the data into
datasheet grid which consists of rows and
columns labeled Field1, Field2, Field3 and so
on. The database software determines the
data type on the data you enter.
Data - types
Text / Alphanumeric: can store any
alphanumeric character (alphabetic or
numeric) and special characters such as
punctuation marks .
eg. name, address , telephone numbers
Numeric: can store numbers. Two types of
numeric data are:
Integer : will store only whole numbers. e.g.
14, 871, -12
Real : will store decimal numbers. e.g. 34.5,
9.25
Currency: can store currency values which allow
currency symbols to be added to the display.
E.g. $20.00
Date: Stores date in different formats.
(dd/mm/yy, dd.mm.yy etc)
e.g. 23/10/12, 23.10.12, 23/10/2012, 23rd
October 2012
Boolean/Logical : can store one of two values
e.g. Yes/No (Y/N), True/False (T/F) ,
Male/Female (M/F)
advantages and disadvantages of
Paper-Based Databases
Advantages :
1. Cheap to set up a paper – based database and
do not need power supply to use them.
2. Don’t need to buy an expensive computer to
use them
3. Most can easily be carried around with you
(as ledgers)
4. You don’t need training to learn how to use
them.
Disadvantages of paper-based databases:
1. They can be lost or misplaced and very hard
to make copies.
2. Hard to correct mistakes made to data
entries.
3. Order of data can get jumbled up. This is
difficult to re-sort.
4. Difficult to search and find specific data.
advantages and disadvantages of
Computer-Based Databases
Advantages :
1. Very easy to make back-up copies
2. Easy to update data and correct mistakes
3. Easy to sort data into order (alphabetical for
example)
4. Very easy and quick to search for specific data
5. They can be secured with passwords.
Disadvantages :
1. They can be expensive to set up (especially if
you hire an expert)
2. The computers need power supply in order
to run the database software.
3. They can be difficult to use so you would need
lots of training.