Chapter 9
DATA AND INFORMATION

Data is a collection of items such as words, numbers, images, and sounds that are not organized and have little meaning individually. Data is processed into information. Information is data that is organized, has meaning, and, therefore, is useful. A student grade report (information), for example, contains several data items, including student identification (ID) number, student first name, student last name, course names, course codes, credit hours, and course grades.

A database is a collection of data organized in a manner that allows access, retrieval, and use of that data. Database software, also called a database management system (DBMS), allows you to create a computerized database; add, change, and delete data; sort and retrieve data from the database; and create forms and reports using the data.

Most organizations realize that data is among their more valuable assets. Without data and information, an organization could not complete many business activities. Information accumulated on sales trends, competitors' products and services, production processes, and even employee skills, for example, allow a company to make decisions and develop, create, and distribute products and services. This information is a valuable resource that would be difficult, if not impossible, to replace. Because information cannot be generated without data, an organization must manage, maintain, and protect its data resources just as it would any other resource. Two critically important aspects of this include ensuring that data has integrity and is kept secure.

Data Integrity

For a computer to output accurate information, the data used to create the information must have integrity. Data integrity is the degree to which data is accurate. If your name is misspelled in a student database, for example, the data is inaccurate and is considered a violation of data integrity.

Although accurate data does not guarantee accurate information, it is impossible to produce accurate information from erroneous data. This computing principle, often referred to as garbage in, garbage out (GIGO), means that, if you enter erroneous data into a computer (garbage in), the computer will produce inaccurate information (garbage out). Data integrity is critical because computers and individuals use information generated from data to make decisions and take actions. When you place an order with a mail‑order company, for example, a sales representative enters the product number for each item you order. If he or she enters an incorrect product number, the warehouse likely will package and ship an item you did not intend to order.

Data Security

Data security involves protecting data so it is not misused or lost. Most schools, for example, have procedures that allow only authorized personnel to access confidential student data. The school also performs backup procedures to protect against the loss of data. Backup refers to making duplicate copies of data, files, programs, or disks, which can be used if the originals are lost, damaged, or destroyed. Making backup copies ensures that you can recover data in a timely manner and that processing can continue. 

THE HIERARCHY OF DATA

Data is organized in a hierarchy in which each higher level consists of one or more elements from the lower level preceding it. Depending on the application and the user, different terms describe the various levels of the hierarchy. Commonly used terms are character, field, record, file, and database. A database contains files, a file contains records, and a record contains fields. Each field is defined by a variety of characteristics, one of which is the field size, or number of characters (bytes) it contains.

A bit represents the smallest unit of data the computer can handle. Eight bits grouped together in a unit comprise a byte. Each byte represents an individual character, such as a number (8), letter (M), punctuation mark (!), or other symbol (@).

A field is a combination of one or more characters and is the smallest unit of data you can access. Typical fields in a database containing data about people include First Name, Last Name, Address, City, State, and Zip. A field often is defined by its data type and field length. The data type specifies the kind of data a field can contain. Common data types include:

��	Text: letters, numbers, or special characters
��	Numeric: numbers only
��	Currency: dollar and cent amounts or numbers containing decimal values
��	Date: month, day and year information
��	Memo: longer text entries
��	Hyperlink: Web address that links to a Web na`,e

The field length is the maximum number of characters a field can contain. The State field, for example, stores text and can contain a total of two characters (for the state abbreviation); a Date field contains a date/time value and can store up to eight characters (for the format, mm/dd/yyyy).

A record is a group of related fields. A student record, for example, is a collection of fields about one student. The record might contain fields such as Student ID, First Name, Last Name, Address, City, State, Zip, Birthdate, Email Address, HS (high school) GPA, HS Graduation Date, and Major.

A key field, or primary key, is a field that differentiates the records in a file. The data stored in a key field contains data that is unique to a specific record. A student record, for example, would use Student ID as a key field because it uniquely identifies each student

A data file, also called a file, is a collection of related records stored on a disk such as a floppy disk, hard disk, or CD‑ROM A school's Student file, for example, would consist of thousands of individual student records. Each student record in the file would contain the same fields.

As defined in previous chapters, file also refers to word processing, spreadsheet, or other application files. These types of files, sometimes called program files, contain programs, instructions, or documents.

A database is a group of related data files. A school's database, for example, might have many individual files related to class scheduling and registration, such as a Student file, a Course file, and a Schedule file. The data files in a database are organized so that a particular database management system can access them.

MAINTAINING DATA
Data maintenance, sometimes called file maintenance, refers to the procedures used to keep data current. Data maintenance procedures include adding records to, changing records in, or deleting, records from a file.

Adding Records

Records are added to a file when additional data is required to make it current. If a school admits a new student, for example, the admissions department would need to add a record containing the data for the new student to the school's Student file. The process required to add this record to the file includes the following steps:

1. An admissions counselor in the admissions department starts a Student Maintenance program that gives him or her access to the database. The admissions counselor then clicks the New Record button, which begins the process of adding a record to the Student file.

2. The admissions counselor assigns a Student ID to the new student. This number serves as the primary key for the student record.

3. The counselor enters data to fill in the fields in the student record. (For purposes of this example, the data entered is kept to a minimum.

4. Once the admissions counselor verifies the data on the screen, he or she clicks the New Record button to add the new student record to the Student file. The program that manages the disk determines where to write the record on the disk. In some cases, the new record is written between existing records in the file.

Changing Records

Generally, you change a record in a file for two primary reasons: (1) to correct inaccurate data or (2) to update older data with newer data.

As an example of the first type of change, assume that an administrative assistant entered a new student's name as Anita Johnson, instead of Anita Johnson. When the student receives her schedule of classes, she notices the error, contacts the registration department, and requests that the department correct the spelling of her name.

To do this, an administrative assistant in the registration department retrieves the record and changes the last name field from Johnson to Johnson. The change thus corrects the inaccurate data and replaces it with accurate data.

A more common reason to change a record is to update older data with newer data. Suppose, for example, that Anita Johnson moves from 423 Western Avenue to 45 Francis Boulevard. The process required to change the address and update Anita Johnson's record includes the following steps:

1. The registration administrative assistant starts the Student Maintenance program.

2. The registration administrative assistant enters Anita Johnson's Student ID of 998‑69‑2286 to display Anita Johnson's record on the screen. If the assistant did not have the Student ID available, he or she could enter the student's last name, which would retrieve all students with that same last name.

3. The program displays data about Anita Johnson. By reviewing this data on the screen, the assistant can confirm that the correct Student ID was entered.

4. The administrative assistant enters the new street address of 45 Francis Boulevard.

5. Once the administrative assistant verifies the data on the screen, she clicks the Save button to change the record in the Student file. The program changes the record on the disk.

Deleting Records

When a record no longer is needed, it is deleted from a file. In this example, a student named Brandon Cloak has requested a transfer to another school. The process required to delete a record from a file includes the following steps:

1. The registration administrative assistant starts the Student Maintenance program.

2. The assistant enters Brandon Cloak's Student ID of 997‑23‑1928 to display his record on the screen.

3. The program displays Brandon Cloak's name and personal data on the screen.

4. Once the assistant verifies that this is the record to be deleted, he or she clicks the Delete Record button to delete the record from the Student file. The actual processing that occurs to delete a record from a file depends on the application. Sometimes, the record is removed from the file immediately. Other times, as in this example, the record is not removed from the file. Instead, the record is flagged, or marked, in some manner so the program will not process it again. In this case, an asterisk (*) is placed at the beginning of the record.

Although the record still physically is stored on the disk, it effectively is deleted because the program will not retrieve it for processing. Flagged records commonly are used in applications where inactive data must be maintained for some period of time. A bank, for example, might flag closed accounts and remove them after one year. Periodically, you should run a utility program that removes flagged records and reorganizes current records. Deleting unneeded records reduces the size of files and creates additional storage space.

Data Validation

Validation is the process of comparing the data to a set of rules or values to determine if the data is accurate. Many programs perform a validity check that analyzes entered data to help ensure that the data is current and accurate. For instance, when an assistant adds or changes data in a record, the database management system performs a validity check to test the entered data.

A range check is an example of a validity check. For example, if you were entering high school grade point averages, you would expect values in the range of 0.0 to 4.0. A value of ‑10 or 85 clearly is outside of the valid range. If the entered data does not pass a validity check, the computer usually displays an error message and asks you to re‑enter the data. Validity checks, also called validation rules, minimize data entry errors and thus enhance the integrity of the data before the data is stored.

Various types of validity checks include alphabetic checks, numeric checks, completeness checks, range checks, consistency checks, and check digits. The following paragraphs describe the purpose of these validity checks.

ALPHABETIC/NUMERIC CHECK An alphabetic check ensures that only alphabetic data is entered into an alphabetic field and a numeric check ensures that only numeric data is entered into a numeric field. For example, data in a City field should contain only alphabetic characters and data in a HS GPA (Grade Point Average) field should contain only numbers.

COMPLETENESS CHECK A completeness check verifies that all required data is present. In many application programs, you cannot leave the Last Name field blank. A completeness check on this field ensures data exists in it.

RANGE CHECK As just described, a range check determines whether a number is within a specified range. When data in the HS GPA field must be between 0.0 and 4.0, any number outside this range is invalid.

CONSISTENCY CHECK A consistency check tests the data entered in two or more fields to determine whether a known relationship between the fields is reasonable. For example, a High School Graduation Date cannot occur before a Birthdate.

CHECK DIGIT A check digit verifies the accuracy of a primary key. Bank account numbers, credit card numbers, and identification numbers often include a check digit. A check digit is a number(s) or character(s) that is appended to or inserted into a primary key value.

The value of a check digit is determined by applying a formula to the numbers in the primary key. A simple formula for computing a check digit would involve adding together the numbers in the primary key. For example, if the primary key is 4359, this check digit formula would add together these numbers (4 + 3 + 5 + 9) for a sum of 21. The formula then would add together the numbers in the result (2 + 1) to generate the check digit of 3. The primary key then would be 43593 (the primary key value, 4359, with the check digit, 3, appended).

When the data entry clerk enters the primary key, 43593, the program applies the formula to the first four digits of the primary key to test if its check digit is valid. If the computed check digit is the same as the entered check digit (3, in this case), the program assumes the entered primary key is valid. If the program computes any other number as the check digit, it displays an error message.

FILE PROCESSING VERSUS DATABASES
Almost all application programs use data that is stored in either files or databases. These two approaches to storing data are discussed in the following sections.

File Processing Systems

In the past, many organizations stored data in files on tape or disk and managed the data using file processing systems. In a typical file processing system, each department within an organization has its own set of files, designed specifically for their own applications, and the records in one file are not related to the records in any other file. Figure 10‑9 illustrates an example of how a school might use a file processing system. The admissions department has its own files to admit a student into the school, and the registration department has its own set of files to register students for classes.

Although organizations have used file processing systems for many years, these systems do have major disadvantages. Two of these disadvantages are data redundancy and isolated data.

��	Data Redundancy. Because each department has it own files in a file processing system, the files often must store the same (redundant) data. Both the admissions department files and the registration department files, for example, must store a student's name and address. Data redundancy wastes resources such as storage space and employee time. Storing the same data in more than one file requires increased storage capacity. When data is added or changed, data maintenance takes more time because employees must update more than one file. Data redundancy also compromises data integrity. If a student relocates, for example, the school must update the student's Address field in the admission and registration files, as well as any other department that contains the student's Address field throughout the school. If the field is not changed in all the files, then discrepancies among the files will exist.

��	Isolated Data. When data is stored in multiple files in multiple departments, often it is difficult to access the data. For example, to generate a report listing the majors of a particular class of students, you would need to access ancl use data in both the admissions department files and the registration department files because the admissions files store the students' major and the registration files store the class rosters. Sharing data from multiple, separate files to generate such a list often is a complicated procedure and typically requires the expertise of an experienced computer programmer.

To overcome these and other problems associated with file processing systems, many companies use the database approach for managing data.

The Database Approach

As previously described, a database is a shared collection of data. With the database approach, many application programs in an Organization could use the data in this single, shared database. A school's database, for example, would contain data about students and courses. 

Users access the data in the database using database software, which often is called a database management system (DBMS). As noted at the beginning of this chapter, a database management system (DBMS) is a software program designed to control access to the database and manage the data resources efficiently. While a user is working with the database, the DBMS resides in the memory of the computer. The next section presents the features of a DBMS in detail.

The database approach overcomes many of the limitations of file processing systems by reducing data redundancy and allowing for sharing of data. These and other advantages of the database approach are presented next.

��	Reduced Data Redundancy. Using the database approach, all data is stored together, which greatly reduces data redundancy. A school database, for example, would store a student's name and address only once. When student data is entered or changed, one employee makes the change once. Figure 10‑11 contrasts a database application to a file processing application with respect to data redundancy.

��	Improved Data Integrity. Because most data is stored in only one location, the database approach increases the data's integrity by reducing the likelihood of introducing inconsistencies. When data in the database is changed, all applications have access to the same updated data.

��	Shared Data. Whereas each application in a file processing environment has its own set of files, the data in a database environment belongs to and is shared by the entire organization. Figure 10‑12 compares how a database application stores data versus a file processing application. Organizations using databases typically set up controls to define who can access, add, change, and delete the data in a database.

��	Reduced Development Time. A database organizes data more efficiently than a file processing system, thus it often is easier and faster to develop programs that use this data. Many database management systems also provide several tools to assist in program development, thus further reducing the development time. The next section discusses these and other DBMS features.

��	Easier Reporting. The database approach allows non-technical users to access and manipulate data. Although computer professionals typically develop larger databases and their associated programs, many computer users are developing smaller databases themselves, without professional assistance.

While it has many advantages, the database approach does have the disadvantages of cost and vulnerability. For one, the initial investment in the hardware and software required for a database usually is high. A large database also can be more complex than a file processing system and thus require trained individuals to develop these applications. These larger databases also require more memory, storage, and processing power than file processing systems.

A second disadvantage of the database approach is its increased vulnerability. Because all data is stored in a single location and shared by application programs, many users depend on the data in the database. If the database is not operating properly or is damaged or destroyed, many users will not be able to perform their jobs. In some cases, certain application programs may cease to operate.

Despite these limitations, many business and home users work with databases because of their tremendous advantages.

DATABASE MANAGEMENT SYSTEMS

As previously discussed, a database management system (DBMS) is a software program or set of programs designed to control access to the database and manage the data resources efficiently. While a user is working with the database, the DBMS resides in the memory of the computer.

Database management systems are available for many sizes and types of computers. Whether designed for a mainframe or a personal computer, every database management system has a number of common features. These features include a data dictionary, and functions such as data maintenance and retrieval, data security, and backup and recovery. The following pages discuss these features of a DBMS.

Data Dictionary

A data dictionary stores data about each file in the database and each field within those files. For each file, a data dictionary stores data including the file name, description, and the file's relationship to other files. For each page field, a data dictionary stores data including the field name, field size, description, type of data (e.g., text, numeric, or date/time), default value, validation rules, and the field's relationship to other fields.

A DBMS uses the data dictionary to perform validation checks and maintain the integrity of the data. When you enter data, the data dictionary verifies that the entered data matches the field's data type. The HS Graduation Date field, for example, must contain a number. A data dictionary also allows you to specify a default value for certain fields. A default value is a value that the DBMS automatically displays in a field. For example, if most students that attend a school live in Indiana, then the DBMS could display a default value of IN in the State field. Displaying a default value minimizes the possibility of errors, because commonly used data items are entered for you. Usually, you can override a default value if it does not apply for a certain record. For example, you can change the value, IN, to MI if you need to add a student that lives in Michigan.

Data Maintenance and Retrieval

A DBMS provides several facilities to enable users and programs to maintain data in and retrieve data from the database. As you have learned, data maintenance involves adding new records, changing data in existing records, and removing unwanted records from the database. To retrieve data from a database, a process called a query, involves extracting specific data from the database and displaying, printing, or storing it. As described in Chapter 2, the capability of retrieving (selecting) database information based on an instruction, called criteria, specified by the user is one of the more powerful features of a database. 

Often, a variety of users, from experienced professionals to non-technical users, need to maintain and retrieve the data in a database. A DBMS thus provides several methods of accessing data, each of which requires varying levels of database expertise. Of these, query languages, forms, and report generators provide a user‑friendly means to maintain and retrieve data from the database. Each of these methods is described in the following paragraphs.

A query language consists of simple, English‑like statements that allow you to specify the data you want to display, print, or store. Although each query language has its own grammar and vocabulary, a person without a programming background usually can learn these languages in a short time. Although you can maintain data with a query language, most users utilize a query language only to retrieve data. To simplify the process, many DBMSs provide wizards to guide a user through the steps of building a query.

Most database management systems also include a feature called query‑by‑example. Instead of learning the grammar and vocabulary associated with a query language, you can use a query‑by‑example (QBE) to extract data from the database. QBEs have a graphical user interface that assists you with retrieving data. Figure 10‑16 shows a sample QBE screen for a query that searches for students that live in Illinois. Later in the chapter, specific query languages are presented in more depth.

A form, sometimes called a data entry form, is a window on the screen that provides areas for entering or changing data in a database. You use forms to retrieve (Figure 10‑16) and maintain (Figure 10‑17) the data in a database. Forms usually provide a means for validating data so as to reduce data entry errors. When designing a form using a DBMS, you can make the form attractive and easy to use by incorporating color, shading, lines, and boxes; varying the fonts and font styles; and using other formatting features.

A report generator, also called a report writer, allows you to design or layout a report on the screen, extract data into the report layout, and then display or print the report. Unlike a form, a report generator is used only to retrieve data. Report generators usually allow you to format report page numbers and dates; report titles and column headings; subtotals and totals; and fonts, font sizes, color, and shading.

Data Security

To ensure that the data in a database is not misused, a DBMS provides mechanisms so that only authorized users can access data at permitted times. In addition, most database management systems allow you to specify different levels of access privileges for each field in the database. These access privileges define the activities allowed by a specific user or group of users.

Access privileges for data involve establishing who can enter new data, change existing data, delete unwanted data, and retrieve data. In the school database, for example, a faculty advisor might have read-only privileges for student transcripts; that is, the advisor could retrieve the transcript data, but cannot change it. The school's registrar, by contrast, would have full‑update privileges to transcript data, meaning that the registrar can retrieve and change the data. Finally, a student would have no access privileges to the transcript data and can neither retrieve nor change the data.

Backup and Recovery

Occasionally, a database is damaged or destroyed because of hardware failure, a problem with the software, human error, or a catastrophe such as fire or flood. A DBMS provides a variety of techniques to restore the database to a usable form in case it is damaged or destroyed.

��	On a regular basis, you should make a backup, or copy, of the entire database. Some DBMSs include backup utilities, while others rely on the backup utilities included with operating systems or those purchased separately.

��	More sophisticated DBMSs maintain a log, or listing, of activities that have affected the database. If you change a student address, for example, the change appears in the log. In this situation, the DBMS places the following in the log: a copy of the student record prior to the change, called the before image; the actual change of address data; and a copy of the student record after the change, called the after image.

��	A DBMS that maintains a log often also provides a recovery utility that uses the logs to restore a database in the event it is damaged or destroyed. Depending on the type of failure, the recovery utility restores the database using rollback or rollforward techniques. In a rollback, also called backward recovery, the log is used to reverse or undo any changes made to the database during a certain period of time, such as an hour. Once the database is restored, you must re‑enter the transactions entered during this period of time. In a rollforward, also called forward recovery, the log is used to re‑enter changes automatically since the last database save or backup. Some database recovery utilities use a combination of both techniques.

RELATIONAL AND OBJECT-ORIENTED DATABASES

Every database and database management system is based on a particular data model. A data model consists of rules and standards that define how data is organized in a database. Five data models are hierarchical, network, relational, object oriented, and object relational.

In the past, databases often were organized according to the hierarchical or network data model. In a hierarchical database, data is organized in a series like a family tree or organization chart. As with a family tree, the hierarchical database has branches made up of parent and child records. Each parent record can have multiple child records. Each child record, however, can have only one parent. A network database is similar to a hierarchical database except that each child record can have more than one parent. 

Because hierarchical and network data	bases offer only limited data access and lack flexibility, database developers prefer two other database models: relational and object oriented. A newer data model, the object relational data model, combines features of the relational and object‑oriented data models. The following sections discuss the features of relational and object‑oriented data models and the databases based on them.

Relational Databases

Today, the most commonly used database, the relational database, is based on the relational data model. A relational database stores data in tables that consist of rows and columns. Each row has a primary key and each column has a unique name.

	A relational database uses terminology different from a file processing environment	concepts.  A relational database developer, for example, refers to a file as a relation, a record as a tuple, and a field as an attribute. 

A user of a relational database, however, refers to a file as a table, a record as a row, and a field as a column. This chapter uses the terms, table, row, and column, when discussing relational databases.

In addition to storing data, a relational database also stores any associations among the data, which are called relationships. With a relational database, you can establish a relationship between tables at any time, provided the tables have a common column (field). You would relate the Student table and the Schedule table, for example, using the Student ID column. In a relational database, the only data redundancy exists in the common columns (fields) that establish relationships.

RELATIONAL ALGEBRA Relational databases often use relational algebra to manipulate data. Relational algebra uses variables and operations to build a new relation. Three commonly used relational operations are projection, selection, and join operations.

To understand the function of the three operations, consider a query that uses these three operations to retrieve a list of students enrolled in ENGL 104. First, the projection operation extracts columns (fields) from a relation, that is, a vertical subset of a table. In the example, the projection operation retrieves the Student ID, First Name, and Last Name columns from the Student table. The selection operation then retrieves certain rows (records) based on the criteria you specify, that is, a horizontal subset of a table. In the example, the selection operation retrieves all rows containing students in ENGL 104 in the Schedule table. The join operation then combines the data from the two queries based on a common column. In the example, the join operation uses the Student ID to combine the data retrieved from the Student and the Schedule tables.

STRUCTURED QUERY LANGUAGE
Relational databases use a query language called Structured Query Language (SQL) to manipulate and retrieve data. SQL includes keywords and rules used to implement relational algebra operations. The SQL statement in Figure 10‑24, for example, would execute a query that retrieves students enrolled in ENGL 104.

Most relational database products for minicomputers and mainframes support Structured Query Language (SQL). Many personal computer database system vendors also have developed or modified existing packages to support SQL.

Object‑Oriented Databases

An object‑oriented database is based on an object‑oriented data model and, thus, maintains objects. An object is an item that can contain both data and the activities that read or manipulate the data. A Student object, for example, might contain data about a student (Student ID, First Name, Last Name, Address, and so on) and instructions on how to print the student record or the formula required to calculate a student's tuition rates. A record in a relational database, by contrast, would only contain data about a student.
 
Two advantages of object‑oriented databases, relative to relational databases, is that they can store more types of data and access this data faster. With an object‑oriented database, you can store unstructured data such as photographs, video clips, audio clips, and documents more efficiently than in a relational database. Further, if you run a query to extract data from an object‑oriented database, the object‑oriented database often returns results more quickly than the same query of a relational database. Examples of applications appropriate for an object‑oriented database include the following:

��	A multimedia database that stores images, audio clips, and/or video clips. A geographic information system (GIS) database, for example, stores maps; a voice mail system stores audio messages; and a television broadcast database stores audio and video clips.

��	A groupware database that stores documents such as schedules, calendars, manuals, memos, and reports. Users can perform queries to search the document contents. One query, for example, might search the schedules for available meeting times.

��	A computer‑aided design (CAD) database that stores data about engineering, architectural, and scientific designs. This data in the database includes a list of components of the item being designed, the relationship among the components, and archived versions of the design drafts.

��	A hypertext database contains text links to other documents, and a hypermedia database also contains graphics, video, and sound. A variety of hypertext and hypermedia databases are accessible via the Web. You can search one of these databases for items such as documents, graphics, audio and video clips, and links to Web pages.

Some companies also are developing object‑relational databases to take advantage of features of both the relational and object‑oriented data models.

OBJECT QUERY LANGUAGE Object-oriented and object‑relational databases often use a query language called object query language (OQL) to manipulate and retrieve data. OQL is similar to SQL in that it uses many of the same rules, grammar, and vocabulary. Because OQL is a relatively new standard query language, however, not all object databases support it.

When you enter search criteria or click a link, the DBMS generates the associated OQL statement that accesses that data from the database. In this case, the database is one on the Web.

DATABASE ADMINISTRATION

Keeping an organization's data centralized in a database requires a great deal of cooperation and coordination on the part of the database users. In file processing systems, if you wanted to track or store data, typically you would just create another file, often duplicating data already stored by someone else, in another file. In a database environment, if you want to track or store data, first you check to see if some or all of the data already is in the database or, if not, how you can add the data to the database. The role of coordinating the use of the database belongs to the data and database administrators.

Role of the Data and Database Administrators

The data and database administrators are responsible for managing and coordinating all database activities. The data administrator (DA) is responsible for designing the database; that is, the DA determines the proper placement of fields, defines relationships among data, and outlines users' access privileges. The database administrator (DBA) is responsible for creating and maintaining the data dictionary, establishing and monitoring security of the database, monitoring the performance of the database, and implementing and testing backup and recovery procedures.

In small organizations, one person often serves as both the data administrator and the database administrator. In larger organizations, the responsibilities of the data and database administrators are split among two or more persons.

Role of the User

One of the user's first responsibilities is to familiarize himself or herself with the data in the existing database. First‑time database users often are amazed at the wealth of information available to help them perform their jobs more effectively.

Another responsibility of the user is to take an active role in specifying additions to the database. The maintenance of an organization's database is an ongoing task that organizations should measure constantly against their overall goals. Users thus should participate in designing the database that will help them achieve those goals.

Database Design Guidelines

A carefully designed database makes it easier for a user to query the database, modify the data, and create reports. Certain database design guidelines apply to databases of all sizes.

QUALITIES OF VALUABLE INFORMATION
As with data, information should have certain characteristics to make it valuable. The characteristics of valuable information include being accurate, verifiable, timely, organized, meaningful, useful, and cost effective.

��	Accurate information is correct information. Inaccurate information often is worse than no information, because inaccurate information can lead to incorrect decisions. Students, for example, assume that their transcripts correctly list their grades. If your transcript incorrectly reports low grades in your major courses, a potential employer might deny you an interview.

��	Verifiable means that you can confirm information. For example, before relying on the cumulative grade point average (GPA) on your transcript, a potential employer might want to check that the GPA is calculated correctly. The potential employer can verify the accuracy of the accumulated GPA by calculating it from the individual semester GPA values.

��	Timely information has an age suited to its use. Your transcript, for example, has value for a potential employer only if the employer receives it in time to make a hiring decision. Although most information loses its value with time, some information, such as information on trends, gains value as time passes and more information is obtained. Your transcript, for example, gains value as you complete more coursework because it reflects your work ethic and dedication over a time period.

��	Organized information is arranged to suit the needs and requirements of the user. An advisor, for example, might want a schedule of classes organized by course codes, while a student would prefer a schedule organized by the day and time the courses meet.

��	Meaningful information is relevant to the person who receives it. Because certain information is meaningful only to specific individuals or groups, you should eliminate

��	unnecessary information and always consider the audience when you are accumulating or reporting information. A graduating student, for instance, probably does not need information on next year's plan for first‑year student housing.

��	Cost‑effective information costs less to produce than the value of the resulting information. Most organizations periodically review the information they produce in reports to determine if the reports provide valuable information. Based on that review, the companies can determine whether to continue, scale back, or even eliminate these reports.

��	Sometimes the value of information is difficult to determine. If an organization cannot determine the value of information, it might choose to generate the information only as people require it, instead of on a regular basis. Another alternative is to make the information available online, thus allowing users to access and print it as they need it.

How Managers Use Information

All employees in an organization need information to perform their jobs effectively; the primary users of information, however, are managers. In an organization, managers are responsible for coordinating the use of resources such as people, money, materials, and information so the organization can operate efficiently and prosper. Managers work toward these goals by performing the four management activities of planning, organizing, leading, and controlling.

��	Planning involves establishing goals and objectives and establishing the strategies or tactics needed to meet these goals and objectives.

��	Organizing includes identifying and bringing together the resources necessary to achieve the plans of an organization. Organizing also involves establishing the management structure of an organization, such as the departments and reporting relationships.

��	Leading, sometimes referred to as directing, involves instructing and authorizing others to perform the necessary work.

��	Controlling involves measuring performance and, if necessary, taking corrective action.

During the controlling activity, managers measure actual performance against a previously established plan. As a result of this measurement, they may revise the plan, which can result in additional organizational and leadership activities. Performance then is measured against the revised plan, and the cycle repeats itself. The four tasks are related and a change in one task usually affects one or more of the other tasks.

Levels of Users

The types of information required by a user often depends on the user's classification in the organization. Users typically are classified into four levels: executive management, middle management, operational management, and non-management employees.

EXECUTIVE MANAGEMENT Executive management, also referred to as senior management or top management, includes the highest management positions in an organization. Executive management is concerned with the long‑range direction of the organization. Senior managers primarily are responsible for strategic decisions that deal with the overall goals and objectives of an organization. Executive management supervises middle management personnel.

MIDDLE MANAGEMENT Middle management is responsible for implementing the strategic decisions of executive management. To do this, middle managers make tactical decisions, also called short‑range decisions, that implement specific programs and plans necessary to accomplish the stated objectives. Middle management supervises operational management

OPERATIONAL MANAGEMENT Operational management supervises the production, clerical, and other non-management employees of an organization. In performing their duties, operational managers make operational decisions that deal with day‑today activities within the organization. The operational decisions should be consistent with and support the tactical decisions made by middle management.

NONMANAGEMENT EMPLOYEES Non-management employees, who include production, clerical, and staff personnel, also need frequent information to perform their jobs. Today, these employees have more information available to them than in the past. This is part of a trend toward giving lower‑level, non-management employees the information they need to make decisions previously made by managers.

TYPES OF INFORMATION SYSTEMS
An information system is a collection of hardware, software, data, people, and procedures that are designed to generate information that supports the day‑to‑day, short range, and long‑range activities of users in an organization. Information systems generally are classified into five categories: office information systems, transaction processing systems, management information systems, decision support systems, and expert systems. The following sections present each of these information systems.

Office Information Systems

An office information system, or OIS (pronounced oh‑eye‑ass), is an information system that uses hardware, software, and networks to enhance work flow and facilitate communications among employees. With an office information system, also described as office automation, employees perform tasks electronically using computers and other electronic devices, instead of manually. With an office information system, for example, a registration department might post the class schedule on the Internet and e‑mail students when the schedule is updated. In a manual system, the registration department would photocopy the schedule and mail it to each student's house.

An office information system supports a range of business office activities such as creating and distributing graphics and/or documents, sending messages, scheduling, and accounting. All levels of users from executive management to non-management employees utilize and benefit from the features of an OIS.

The software an office information system uses to support these activities include word processing, spreadsheets, databases, presentation graphics, e‑mail, Web browsers, Web page authoring, personal information management, and groupware. Office information systems use communications technology such as voice mail, facsimile (fax), videoconferencing, and electronic data interchange (EDI) for the electronic exchange of text, graphics, audio, and video. An office information system also uses a variety of hardware, including computers equipped with modems, video cameras, speakers, and microphones; scanners; and fax machines.

Transaction Processing Systems

A transaction processing system (TPS) is an information system that captures and processes data generated during an organization's day‑to‑day transactions (Figure 10‑31). A transaction is a business activity such as a deposit, payment, order, or reservation. Clerical staff typically perform the activities associated with transaction processing, which include the following:

1. Recording a business activity such as a student's registration, a customer's order, an employee's timecard, or a client's payment

2. Confirming an action or triggering a response, such as printing a student's schedule, sending a thank‑you note to a customer, generating an employee's paycheck, or issuing a receipt to a client

3. Maintaining data, which involves adding new data, changing existing data, or removing unwanted data

Transaction processing systems were among the first computerized systems developed to process business data—a function originally called data processing. Usually, the TPS computerized an existing manual system to allow for faster processing, reduced clerical costs, and improved customer service.

The first transaction processing systems usually used batch processing. With batch processing, transaction data is collected over a period of time and all transactions are processed later, as a group. As computers became more powerful, system developers built online transaction processing systems. With online transaction processing (OLTP), the computer processes transactions as they are entered. When you register for classes, your school probably uses OLTP. The registration administrative assistant enters your desired schedule and the computer immediately prints your statement of classes. The invoices, however, often are printed using batch processing, meaning all student invoices are printed and mailed at a later date.

Today, most transaction processing systems use online transaction processing. Some routine processing tasks such as calculating paychecks or printing invoices, however, are performed more efficiently on a batch basis. For these activities, many organizations still use batch processing techniques.

Management Information Systems

While computers were ideal for routine transaction processing, managers soon realized that the computers' capability of performing rapid calculations and data comparisons could produce meaningful information for management. Management information systems thus evolved out of transaction processing systems. A management information system, or MIS (pronounced em‑eye‑ass), is an information system that generates accurate, timely, and organized information so managers and other users can make decisions, solve problems, supervise activities, and track progress. Because it generates reports on a regular basis, a management information system sometimes is called a management reporting system (MRS).

Management information systems often are integrated with transaction processing systems. To process a sales order, for example, the transaction processing system records the sale, updates the customer's account balance, and makes a deduction from inventory. Using this information, the related management information system can produce reports that recap daily sales activities; summarize weekly and monthly sales activities; list customers with past due account balances; graph slow or fast selling products; and highlight inventory items that need reordering. A management information system focuses on generating information that management and other users need to perform their jobs.

An MIS generates three basic types of information: detailed, summary, and exception. Detailed information typically confirms transaction processing activities. A Detailed Order Report is an example of a detail report. Summary information consolidates data into a format that an individual can review quickly and easily. To help synopsize information, a summary report typically contains totals, tables, or graphs. An Inventory Summary Report is an example of a summary report.

Exception information filters data to report information that is outside of a normal condition. These conditions, called the exception criteria, define the range of what is considered normal activity or status. An example of an exception report is an Inventory Exception Report that notifies the purchasing) department of items it needs to reorder. Exception reports help managers save time because they do not have to search through a detailed report for exceptions. Instead, an exception report brings exceptions to the manager's attention in an easily identifiable form. Exception reports thus help them focus on situations that require immediate decisions or actions.

Decision Support Systems

Transaction processing and management information systems provide information on a regular basis. Frequently, however, users need information not provided in these reports to help them make decisions. A sales manager, for example, might need to determine how high to set yearly sales quotas based on increased sales and lowered product costs. Decision support systems help provide information to support such decisions.

A decision support system (DSS) is an information system designed to help users reach a decision when a decision‑making situation arises. A variety of DSSs exist to help with a range of decisions.

A decision support system uses data from internal and/or external sources. Internal sources of data might include sales, manufacturing, inventory, or financial data from an organization's database. Data from external sources could include interest rates, population trends, costs of new housing construction, or raw material pricing. Users of a DSS, often managers, can manipulate the data used in the DSS to help with decisions.

Some decision support systems include query languages, statistical analysis capabilities, spreadsheets, and graphics that help you extract data and evaluate the results. Some decision support systems also include capabilities that allow you to create a model of the factors affecting a decision. A simple model for determining the best product price, for example, would include factors for the expected sales volume at each price level. With the model, you can ask what‑if questions by changing one or more of the factors and viewing the projected results. Many people use application software packages to perform DSS functions. Using spreadsheet software, for example, you can complete simple modeling tasks or what‑if scenarios.

A special type of DSS, called an executive information system (EIS), is designed to support the information needs of executive management. Information in an EIS is presented in charts and tables that show trends, ratios, and other managerial statistics (Figure 10‑34). Because executives usually focus on strategic issues, EISs rely on external data sources, such as the Dow Jones News/Retrieval service or the Internet. These external data sources can provide current information on interest rates, commodity prices, and other leading economic indicators.

To store all the necessary decision-making data, DSSs or EISs often use extremely large databases, called data warehouses. A data warehouse stores and manages the data required to analyze historical and current business circumstances.

Expert Systems

An expert system is an information system that captures and stores the knowledge of human experts and then imitates human reasoning and decision‑making processes for those who have less expertise (Figure 10‑35). Expert systems are composed of two main components: a knowledge base and inference rules. A knowledge base is the combined subject knowledge and experiences of the human experts. The inference rules are a set of logical judgments applied to the knowledge base each time a user describes a situation to the expert system (Figure 10‑36).

Although expert systems can help decision‑making at any level in an organization, non-management employees are the primary users, who utilize them to help with job‑related decisions. Expert systems also successfully have resolved such diverse problems as diagnosing illnesses, searching for oil, and making soup.

Expert systems are one part of an exciting branch of computer science called artificial intelligence. Artificial intelligence (AI) is the application of human intelligence to computers. AI technology can sense your actions and, based on logical assumptions and prior experience, will take the appropriate action to complete the task. AI has a variety of capabilities, including speech recognition, logical reasoning, and creative responses.

Experts predict that AI eventually will be incorporated into most computer systems and many individual software applications. Many word processing programs, for example, already include speech recognition.

Integrated Information Systems

With today's sophisticated hardware, software, and communications technologies, it often is difficult to classify a system as belonging uniquely to one of the five information system types discussed. Much of today's application software, for instance, supports transaction processing and generates management information. Other applications provide transaction processing, management information, and decision support. Although expert systems still operate primarily as separate systems, organizations increasingly are consolidating their information needs into a single, integrated information system.

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