data types

querying a database

Table that Data

1. Contact name and number of USA products

2. Product name of products over $20

3. Product name of products with over 30 in stock

creating a basic database

Above is an annotation of a database.

For the task, we were required to create a contact database. Types of fields included: Surname, First Name, Mobile, Home, DOB, Street, Suburb and Postcode.

Different data types used were:
Text - Surname, First Name, Street, Suburb
Number - Mobile, Home, Postcode
Date/time - DOB

data type

As it suggests, a data type is a type of data. A data type is a somewhat of a storage format which consists of specific types or range of values. It is the classification/grouping of similar and different types of information. This is done in order to make it easer to distinguish different types of data. Internal codes are used to keep track of that data that are being processed.

Common types of data include:
• integers
• floating point numbers
• characters
• strings
• arrays

data dictionary

A data dictionary is a file that describes the basics of a database. It contains a list of all information: all files in a database, number of records in each file, and names and types of each field. Most data dictionaries are hidden from users to prevent the accidental alteration/destruction of its contents. They don't contain data from the database but is able to keep information for management. Without one, the DBMS can't access data from the database.

DBMS

DataBase Management System

A database management system is a collection of programs/applications which enable you to select, organise and enter/edit data in a database.

Examples of database applications include:
• computerised library systems
• automated teller machinse
• flight reservation systems

report

A database report presents information that has been retrieved from a table or query. The information is displayed in a formatted and organised manner (eg. a table).

query

A query is a request for information on a database. It is the main mechanism for retrieving information, consisting of questions 'asked' to the database.

Three methods for posing queries include:
• choosing parameters (characteristics) from a menu (list of options/commands)
• query by example (QBE) - specifying fields that define the query
• query language - must be written in a special query language

file

A file is a collection of data/information with a name. Most information stored in a computer must be in a file so that they can be viewed.

Files store different types of information depending on the file type. Types of files include:
• data files
• text files
• program files
• directory files
• etc

record

Database records are complete sets of information. They are composed of fields, that each contain information. A set of records makes a file.

Records are sometimes referred to as tuples.

field

A database field is a space in a fixed/known location where a specific item or location is found. Fields are the smallest units of information that is accessable.

For example, when you're filling out a form online, you have to fill in your information in fields. Some fields are required where you have to put data/information, some are optional that you can leave blank, and some are calculated.

Examples include a tax form which contains several fields like:

• name

• Social Security number

• income

Do you see any dangers or disadvantages in this online version of the yellow pages?

• because you can easily find other people's addresses, other people can just as easily find your address - these people may be the kind of people you don't want to be involved with

• problems may arise with the website and the electronic Yellow Pages may not be available for access

• doesn't list how recent the current information is - so there's no knowing if the information is accurate

• certain people in society (eg. poorer, elderly) don't/won't have access to internet connection

What can you see as some of the advantages of using this electronic database compared to the conventional paper based version of the yellow pages?

• it is much easier to access and find the online Yellow Pages because it can be found on the web and its information isn't contained in one paper based version

• finding a location is much quicker because all it takes is to type the relevant information - as opposed to the paper based version that will need more time because there are many pages to flip through

• information is subject to change and the information on the electronic Yellow Pages can swiftly be changed - different to the paper based version

• electronic Yellow Pages contain maps which can provide an idea of the distances between different points

• electronic Yellow Pages can provide directions, starting from any location

• more environmentally friendly because the electronic Yellow Pages doesn't use hundreds of paper like the paper based version

• saves space

Is the yellow/white pages a database?

Yes, it is. This is because it consists of data that can be easily accessed. Like a phonebook, Yellow Pages have organised data (that are related) which makes it easier to find specific locations. The desired data is easily found since Yellow Pages asks for 'What' it is you are looking for and 'Where' it is.

Yellow Pages #4

Just for fun try the white pages and see if you can find a map of you or your friends house.

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Yellow Pages #3

You want the phone numbers of some motels in Noosa QLD. But of course your phone book only has NSW numbers?

Hotel Laguna

ph: (07) 5447 3077

Noosa Heads Motel

ph: (07) 5440 4550

Noosa Village Motel

ph: (07) 5447 5800

Seahaven Beachfront Resort

ph: (07) 5447 3422

Yellow Pages #2

Sally lives in Merrylands on Fowler Rd. and she wants to know the closest florist to where she lives. Help her out (see if you can get her a map).

M & A Freshcut Flowers

91a Fowler Rd, Merrylands NSW 2160

ph: (02) 9892 1564

Yellow Pages #1

I know there is a computer shop in the main street of Katoomba (Katoomba St.), but I don't know its name. See if you can find the number for me.

Bennett Office Supplies

122 Katoomba St, Katoomba NSW 2780

ph: (02) 4782 2228