Chapter 12 Accessing Databases. 2Practical PC 5 th Edition Chapter 12 Getting Started In this Chapter, you will learn: − What’s a database − About database

Chapter 12Accessing Databases

2 Practical PC 5th Edition Chapter 12

Getting Started

• In this Chapter, you will learn:− What’s a database− About database software− How to create your own database− To create databases with spreadsheet software− About databases on the Web and on CDs− About Hardware: CDs and DVDs


What’s a database?

• A database is a collection of data• Structured databases contain information that is organized as

fields, records, and files– A field contains a single piece of information– A record contains fields of information about a single “entity” in the

database– A group of similarly structured records form a fie

• A relational database allows you to store information for two or more different types of records and form a link between them– Each record type is stored in a table

• For example, a video store database may include a table of customers and a table of videos

• When a customer checks out a video a link is made between the two tables


What’s a database?

Database with linked tables


Do I need database software?

• Database software provides a set of tools to enter and update information in fields– Also called a database management system– You can enter, delete, sort, and search for records– You might access a product database when shopping

online or a bank database at an ATM machine• Database software offers a wealth of data

management capabilities– Requires a substantial learning commitment– For simple files, you may be able to use the database

modules in Microsoft Works – You can also use spreadsheet software for simple

databases


How would I create my own database?

• Creating a database consists of two tasks:– Creating the file structure to hold the data– Entering the data

• A file structure is a specification for the database fields and their characteristics– You’ll need to assign a name to each field– You may also need to specify the data type and maximum field length

• You then enter the data carefully and consistently– Be consistent with symbols, capitalization, categories, and

abbreviations– Compare onscreen data against the original documents


How would I create my own database?

Entering data in Access


Can I really create databases with spreadsheet software?

• You can use spreadsheet software to maintain files of information

• You cannot use it to join files or tables together to create a relational database

• You can use the Form View feature in spreadsheet software to view each row as a “card” containing a series of fields

• You can also filter the data, which is more complicated, but useful for creating reports that show only selected data


What about databases on the Web and on CDs?

• You’ll find many databases on the Web– Look up your old roommate in a phone-book-style

database– Look up flights in a database of flight schedules– Check the value of your car in a digital “Blue Book”

• Web and CD databases can overlap– Web is optimal for data that is constantly changing– On the Web databases can actively collect information– CDs provide a low cost distribution method for less

changeable data– CDs are more private since your access of the data is not

tracked by a cookie or a Web site


What about databases on the Web and on CDs?

Web and CD databases


Hardware: CDs and DVDs

• CDs − Originally invented to hold music− CD-ROM

• Computer CDs are sometimes called CD-ROMs to distinguish them from audio CDs

• CD-ROM is an abbreviation of “compact disc read-only memory” • CD-ROMs are preloaded with data and cannot be used to store

additional data



• CDs (continued)− CD-R and CD-RW

• CD-R (CD-recordable) data cannot be changed once it is recorded

• CD-RW (CD-rewritable) allows you to record and then later change the data

• CD-Rs are considered to be more dependable since some machines have trouble reading CD-RWs created on other machines

• Most CD drives have R and RW capabilities, and the speeds of the drives vary



CD Drive Speed Varies



• DVDs− Originally invented to replace VHS tapes− Digital Video Disc

• Storage capacity much greater than a CD-ROM disc• Data can be stored in one of four formats depending on number

of sides and number of layers used• DVDs are available in read-only, recordable, and rewritable

formats• High Definition DVD is a high-capacity DVD format designed for

high definition videos and data storage



DVD storage capacity depends on sides and layers used



• Blu-ray disk is a competing format to High Definition DVDs

• DVD drives often work with more than one type of optical media− DVD+R/RW / CD-R/RW combination drive can

read and record on both DVDs and CDs− Most new PCs include a combination drive


Who owns information about me?

• What do you think?– Can you identify an actual incident when you

discovered that data about you had been distributed without your approval?

– Do you accurately fill out questionnaires that you encounter on the Web?

– Do you think that you have the right to be consulted before anyone distributes information about you?


Chapter Summary

• You should now be able to:− Understand what is a database− Use database software− Create your own database− Create databases with spreadsheet software− Understand about databases on the Web and

on CDs− Understand the difference CDs and DVDs

Documents

Chapter 12 Accessing Databases. 2Practical PC 5 th Edition Chapter 12 Getting Started In this Chapter, you will learn: − What’s a database − About database