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 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

3Practical PC 5 th Edition Chapter 12 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

4Practical PC 5 th Edition Chapter 12 What’s a database? Database with linked tables

5Practical PC 5 th Edition Chapter 12 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

6Practical PC 5 th Edition Chapter 12 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

7Practical PC 5 th Edition Chapter 12 How would I create my own database? Entering data in Access

8Practical PC 5 th Edition Chapter 12 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

9Practical PC 5 th Edition Chapter 12 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

10Practical PC 5 th Edition Chapter 12 What about databases on the Web and on CDs? Web and CD databases

11Practical PC 5 th Edition Chapter 12 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

12Practical PC 5 th Edition Chapter 12 Hardware: CDs and DVDs 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

13Practical PC 5 th Edition Chapter 12 Hardware: CDs and DVDs CD Drive Speed Varies

14Practical PC 5 th Edition Chapter 12 Hardware: CDs and DVDs 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

15Practical PC 5 th Edition Chapter 12 Hardware: CDs and DVDs DVD storage capacity depends on sides and layers used

16Practical PC 5 th Edition Chapter 12 Hardware: CDs and DVDs 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

17Practical PC 5 th Edition Chapter 12 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?

18Practical PC 5 th Edition Chapter 12 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