Unit 3: Database Applications and Implications

 LEARNING OBJECTIVES

After completing this unit, you should be able to:

• Explain what a database is and what it can be used for
• Describe different kinds of database software, from simple file managers to complex relational databases
• Describe database operations for storing, sorting, updating, querying, and summarizing information
• Explain how databases threaten our privacy

Bill Gates Rides the Digital Wave:

In the early days of the personal computer revolution, Bill Gates and Paul Allen formed a company called Microsoft to produce and market a version of the BASIC programming language for microcomputers. Microsoft's biggest break came when its operating system MS-DOS (for MicroSoft Disk Operating System) became an industry standard.

Today Bill Gates and Microsoft dominate the personal computer software industry, selling operating systems, programming languages, and application programs for a variety of desktop computers. Microsoft is now working on CD-ROM and other technologies that make computers easier to use and more accessible.

What Good is a Database?

A database program is an information manager that can help alleviate information overload. Databases make it possible for people to store, organize, retrieve, communicate, and manage information in ways that wouldn't be possible without computers.

Computerized databases offer several advantages over their paper-and-pencil counterparts:

• Databases make it easier to store large quantities of information.
• Databases make it easier to retrieve information quickly and flexibly.
• Databases make it easy to organize and reorganize information.
• Databases make it easy to print and distribute information in a variety of ways. 

Database Anatomy:

• For our purpose a database is a collection of information stored in an organized form in a computer, and a database program is a software tool for organizing storage and retrieval of that information.
• A database is composed of one or more files. A file is a collection of related information; it keeps that information together the way a drawer in a file cabinet does. (The term file sometimes causes confusion because of its multiple meanings. In this Unit, file refers specifically to a data file created by a database program.)
• A database file is a collection of records. A record is the information relating to one person, product, or event. Each discrete chunk of information in a record is called a field.
• The type of information a field can hold is determined by its field type. For example, the author field in the library database would be defined as a text field. The field specifying the number of copies of a book would be defined as a numeric field. A date-of-purchase field might be a date field.
• In addition to these standard field types, many modern database programs allow fields to contain graphics, digitized photographs, sounds, or even video clips. Computed fields contain formulas similar to spreadsheet formulas&endash;they display values calculated from values in other numeric fields.
• Most database programs provide more than one way to view the data, including views that show one record at a time and views that display several records in lists similar to a spreadsheet. In any view, fields can be rearranged without changing the underlying data.

Database Operations:

Once the structure of a database is defined, it's easy to get information in&endash;it's just a matter of typing. Most database programs can easily import or receive data in the form of text files created with word processors, spreadsheets, or other databases. When information changes or errors are detected, records can be modified, added, or deleted.

The challenging part of using a database is retrieving information in a timely and appropriate manner. One way to find information is to browse through the records of the database file just as you would if they were paper forms in a notebook. Most database programs include a variety of commands and capabilities that make it easy to get the information you need when you need it.

 

Database Queries

The alternative to browsing is to ask the database for specific information. In database lingo, an information request is called a query. A query may be a simple search for a specific record or request to select all of the records that match a set of criteria. Once you've selected a group of records, you can browse through it, produce a printout, or do just about anything else you might do with the complete file.

 

Sorting Data

Sometimes it's necessary to rearrange records to make the most efficient use of data. A sort command allows you to arrange records in alphabetic or numeric order based on values in one or more fields.

Printing Reports, Labels, and Form Letters

In addition to displaying information on the screen, database programs can produce a variety of printouts. The most common type of database printout is a report&endash;an ordered list of selected records and fields in an easy-to-read form.

Database programs can also be used to produce mailing labels and customized form letters. Most database programs don't actually print letters; they simply export or transmit the necessary records and fields to word processors with mail merge capabilities, which then take on the task of printing the letters.

Complex Queries

Queries may be simple or complex, but either way they must be precise and unambiguous. The exact method for performing a query depends on the user interface of the database software.

Most programs allow the user to specify the rules of the search by filling in a dialog box or a blank on-screen form. Some require the user to type the request using a special query language that's more precise than English. Most database management programs now support SQL (Structured Query Language)&endash;the standard for programming complex queries. Many modern users are insulated from the complexities of the query language by graphical user interfaces that allow point-and-click queries. Many database programs include programming languages so queries can be included in programs and performed automatically when the programs are executed. Some programs even accept queries generated by other software applications.

Special-purpose Database Programs

Many specialized database programs are sold as personal information managers (PIMs) or electronic organizers. A personal information manager can automate some or all of these functions:

• address / phone book
• appointment calendar
• to-do list
• miscellaneous notes

The user interface of personal information management software is especially important because of the constant interaction between the user and the software.

From File Managers to Database Management Systems:

A file manager is a program that allows users to work with one file at a time.

A true database management system (DBMS) is a program or system of programs that can manipulate data in a large collection of files, cross-referencing between files as needed. A database management system can be used interactively, or it can be controlled directly by other programs.

With a database management system there's no need to store redundant information in every file. Instead a key field is shared by all files that use the same data. If redundant data changes, it need only be recorded in one place.

What Makes a Database Relational?

To most users a relational database program is one that allows files to be related to each other so that changes in one file are reflected in other files automatically. To computer scientists the term relational database has a technical definition related to the underlying structure of the data and the rules specifying how that data can be manipulated.

The structure of a relational database is based on the relational model&endash;a mathematical model that combines data in tables. Other kinds of database management systems are based on different theoretical models, with different technical advantages and disadvantages.

The Many Faces of Databases:

Large databases can contain hundreds of interrelated files. Fortunately a database management system can shield users from the complex inner workings of the system, providing them with only the information and commands they need to get their jobs done. In fact, a well-designed database puts on different faces for different classes of users.

Downsizing and Decentralizing:

The earliest file management programs could only do batch processing, which required users to accumulate transactions and feed them into computers in large batches. These batch systems weren't able to provide the kind of immediate feedback we expect today.

Today disk drives, inexpensive memory, and sophisticated software have allowed interactive processing to replace batch processing for most applications. Users can now interact with data through terminals, viewing and changing values in real time. Batch processing is still used for printing periodic bills, invoices, and reports and for making backup copies of data files. But for applications that demand immediacy, such as airline reservations, banking transactions, and the like, interactive, multiuser database systems have taken over.

Until recently most databases were housed in mainframe computers. But for a growing number of organizations, the traditional centralized database on a mainframe system is no longer the norm.

Some companies use a client/server approach. Database software in client desktop computers works with files stored in central server databases on mainframes, minicomputers, or desktop computers.

Other companies use distributed databases that use data strewn out across networks on several different computers.

From the user's point of view, the differences between these approaches may not be apparent.

 

Tomorrow's Databases?

Many computer scientists believe that the relational data model may be supplanted in the next decade by an object-oriented data model, and that most future databases will be object-oriented databases rather than relational databases. Instead of storing records in tables and hierarchies, object-oriented databases store software objects that contain procedures (or instructions) along with data. Object-oriented databases often are used in conjunction with object-oriented programming languages.

Tomorrow's databases will be able to respond intelligently to commands and queries issued in natural human language.

Rules of Thumb: Dealing with Databases:

A few commonsense rules when working with file managers or relational database management systems are:

• Choose the right tool for the job.
• Think about how you'll get the information out before you put it in.
• Start with a plan, and be prepared to change it.
• Make your data consistent.
• Databases are only as good as their data.
• Query with care.
• If at first you don't succeed, try another approach.

The Privacy Problem:

Businesses and government agencies spend billions of dollars every year to collect and exchange information about you and me. For most of us this data is out of sight and out of mind. But every day lives are changed because of these databases.

Big Brother and Big Business:

With modern networked computers it's easy to compile profiles by combining information from different database files. When files share a unique field, record matching is trivial and quick. Sometimes the results are clearly beneficial. But these benefits come with at least three problems:

• Data errors are common.
• Data can become nearly immortal.
• Data isn't secure.

Protection against invasion of privacy is not explicitly guaranteed by the U.S. Constitution. Legal scholars agree that the right to privacy&endash;freedom from interference into the private sphere of a person's affairs&endash;is implied by other constitutional guarantees, although debates rage about exactly what this means.

Federal and state laws provide various forms of privacy protection, but most of those laws were written years ago. When it comes to privacy violation, technology is far ahead of the law.

Rules of Thumb: Your Private Rights:

Here are a few tips for protecting your right to privacy:

• Your Social Security number is yours; don't give it away.
• Don't give away information about yourself.
• Say no to direct mail and phone solicitations.
• To maximize your privacy, minimize your profile.
• If you think there's incorrect or damaging information about you in a file, find out.
• Support organizations that fight for privacy rights.

batch processing, browse, centralized database, client/server database, computed field database

database management system (DBMS), database program, data warehouse, distributed database

electronic organizer, export data, field, file, file manager, geographical information system (GIS)

import data, interactive processing, key field, mail merge, object-oriented database

personal information manager (PIM), query, query language

real time, record, record matching, relational database, report, right to privacy

search, select (records), sort, SQL (Structured Query Language)

 Computer Literacy On-Line

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