Database Management

Although the information stored in databases may give the organization the ability to do many things that would be otherwise impossible, it is database management systems that make the data available to users and allow them to access and process them so that they can be used in business applications. Database management systems are software programs that allow users to manage the data in a database. Database management systems are designed to increase the accessibility of data and the productivity of the user. To do this, database management systems integrate databases so that users can get the answers to questions they need, reduce data redundancy, enable the sharing of information among multiple users at various locations, and maintain the integrity (a combination of security and reliability) of the database.

Business Information Systems

Overview

In the information age, it has become a truism that information is power. If an organization has information about the needs of the marketplace, it can design a better widget and earn a larger market share. If an organization has information about what the competition is doing, it can develop a strategy to meet or exceed their competitors, thereby winning a competitive advantage. If an organization has information about prospective and current customers, it can build relationships with them and influence their perceptions of the organization and its products and services.

Databases & Their Uses

Information technology (IT) enables organizations to do these things and more in ways that were not previously possible when data had to be tracked manually. Through the use of computers and communications networks in the creation, storage, and dispersal of data and information, the flow of information and data between people or departments can be facilitated better than ever before. Arguably, however, it is databases (collections of data items used for multiple purposes which are stored on a computer) that give information systems their power. Databases can be used in a wide variety of situations ranging from personal productivity to enterprise-wide applications that are used by multiple users and maintained by IT professionals. The information in databases is managed by software programs called database management systems. These systems are designed to increase the accessibility of data and the productivity of the user.

There are a number of reasons to use databases. First, databases are the sine qua non of information systems because they are where the data used by the system are stored. Unless data are accessible, they cannot be retrieved and used. For example, homeowners often need to hire contractors to do various jobs ranging from painting the shutters to fixing the plumbing. Although some contractors are both honest and professional, others are not. Therefore, many homeowners ask their neighbors for recommendations about who they have used successfully for similar jobs. This information is often stored away on bits or paper or business cards or even entered into an address book. However, when the roof starts leaking and the grand piano is getting wet, it is often difficult to remember where the scrap of paper with the name of the recommended roofer is or even which neighbor recommended the company. Databases help solve this problem by storing all data about a particular subject in one location.

Data Retrieval

Just knowing where the data are located, however, is insufficient. One must also be able to retrieve them. For example, if Harry Homeowner knows that the roofer's information is in the kitchen junk drawer, he still may have to go through many pieces of paper with various contractors' contact information on them before he finds the information he needs. In addition, Harry may find that the kitchen drawer has information on more than one roofer, so he needs to remember which one was recommended and which one was not. In information technology terms, this process is called retrieving the data. To retrieve data from a database, one needs to query the system. A query is a search question used by a database management system to specify which data are to be retrieved from the database. So, for example, if Harry had a database of contractor information, he could query the system to retrieve all the data on roofing contractors. Unless there only a handful of cards in Harry's kitchen drawer, the process of querying a database is likely to produce the name of the contractor much more quickly than is manually searching through the kitchen drawer. Harry could search the database using a number of different queries, including the contractor's name or specialty (e.g., roofing or roof repair). If, on the other hand, the grand piano in the living room was getting soaked because of leaky plumbing, Harry could just as easily query the database for plumbers and retrieve that information.

Database Editing

Like the rest of life, the information in a database is not static. A-1 Roofers may move and change their address or add a website that Harry may want to include in his database. Or Harry may try A-1 Roofers and find that they have a new employee who does not do a good job or that they have changed their price structure and their services are no longer affordable. As a result, Harry may want to include a notation with their other information to specify that he does not want "Mike" to come out or that A-1 is overpriced. To do this, Harry needs to edit the database -- that is, he needs to add, delete, or change the information that is stored in the database. Not only can the specific data of a record be edited, it can also be reclassified so that the database can be organized in a different manner. For example, A-1 Roofing may decide to expand the services that it offers and change its name to A-1 Contracting. Harry could edit its record in the database to reflect the name change and also add the category "drywall repair" to the record. That way, when Harry decides that he does not want to repair the damaged walls that resulted from the leak (whether it is a plumbing or roofing problem) himself, when he queries the database for drywall repair, A-1 Contracting will be retrieved as part of the search.

Information Distribution

In addition, database management systems are used to distribute data and information. For example, Harry may only want to view a list of roofing contractors and their phone numbers, or he may want to view details of their contact information and any comments he has input into the system about them. Although Harry may just want this information to be displayed on the computer screen for his purposes, if he wants to pass on the information to a neighbor who also has a leaky roof, he way want to print out the information in any one of a number of different formats. In a more complex example, if Harry were the marketing manager of a large roofing supply company, he could use a database to generate form letters and mailing labels so that he could advertise the company's products and services to hundreds or even thousands of contractors. He could also transmit information about local roofing companies to corporate headquarters using a communications network.

Special Purpose Databases

In addition to general purpose database systems that are managed with generic database management system software that can be applied to virtually any database, there are also special purpose databases that are designed for a specific use. Directories list information by category, such as a telephone directory that lists names of individuals or organizations and contact information for where they can be located. Personal information managers are database management system that allows users to manage data to organize their personal activities. For example, personal information managers may contain a contact list of names, addresses, phone numbers, e-mail addresses, and other details for business and personal contacts. Database management software can retrieve the contact information for a single entry, allow the user to browse the entries, or bring up entries that have been classified into specific categories (e.g., home repair). Personal information managers often also have a calendar function that can span several years, record dates and times for meetings, appointments, deadlines, and other events that the user wishes to remember. The information in these databases is typically tracked by the minute and also offers different views of the calendar, such as by day, workweek, calendar week, and month. This information can be viewed onscreen or printed out. In addition, many personal information managers allow users to keep track of the tasks that they need to accomplish and organize them according to due date or priority. Users are also often able input notes or comments into the database rather than into a physical notebook. These features are often built into personal digital assistants, handheld computers, and smartphones, as well as many personal computers. In addition, data can often be synchronized between devices. For example, notes taken on the road and input into a mobile device can be transferred to a personal computer and manipulated there. Similarly, schedule information can be input into a personal computer and transferred to the digital device so that the user can keep track of appointments when away from the office.

Database Management Systems

Database management systems work in tangent with other programs within an information system, maintaining the structure of the data and working with the other programs so that the data can be located and retrieved. Database management systems also accept new data from other application programs and write these into the appropriate storage location on the system.

Figure 1 shows the relationship between a database management system and the other programs in the computer system. An application program (a software program that performs functions not related to the running of the computer itself) requests the database management system to locate and retrieve data according to a schema -- a predefined structure. The database management system then interacts with the operating systems for the computer and the network to transmit the data over the network.

Objectives of Database Management Systems

Database management systems have several objectives.

* First, they are designed to integrate databases so that users can get the answers they need. This is necessary because data are often stored in multiple databases. To process a query or create a report, therefore, the data from the disparate sources must first be merged.

* Database management systems are also designed to reduce redundancy in the database. For example, one table in a university's student database may contain contact and demographic information for students while another table may contain information about the students' grades. To generate report cards, home addresses would be pulled from one table and current grades from another. The data for the student might be linked through a unique student identification number that is in both tables. Although it would be possible for both tables to contain the student address information, this redundancy would be unnecessary and take up space in a database that could be used to store different data or information. Using a unique identifier to link the tables also eliminates the unfortunate possibility of sending the wrong grades to students who have the same names. This unique identifier is what allows a relational database management system to relate data and information in one table to data and information in another table. In addition, redundancy increases the possibility of errors. For example, if a student's address were to change, the address fields in both tables would have to be updated. This not only increases the possibility of errors, but also increases the cost of maintaining the database.

* Another objective of database management systems is to share information among multiple users at various locations. Database management software allows information to be stored once and retrieved and processed many times. This means that storage capacity and concomitant maintenance costs are reduced and helps ensure that data are consistent across the system.

* Database management systems are also designed to maintain the integrity (a combination of security and reliability) of the database. One way that database management systems do this is through security measures such as only allowing authorized personnel access to data.

* Database management systems also help to ensure database reliability by specifying how data are to be entered into the database and making sure that the data are correct.

* In addition, database management systems help ensure database integrity by requiring the database to be regularly backed up in case of damage or loss.

Applications

The Language of Databases

The goal of databases is to make data and information accessible as efficiently as possible. As with any technical subject, database management has a language all its own. An entity is a person, place, thing, event, or condition about which a database houses information. For example, a university may have a database that describes various attributes of its students. In this database, "student" would be the entity. Entities in the database are described by various attributes that are facts or characteristics about the entity. For example, a database may include the student's name, street address, city, state, zip code, identification number, telephone number, date of birth, residency status, and the name of an emergency contact.

Once the specific attributes of an entity are stored in a database, they are referred to as data items. For example, the student database may include entries for Thomas O'Rafferty, John Smith, and other students at the university. A record is a complete set of information about an entity and is made up of individual fields. These are columns of data in a database file. For example, a database may contain the field "student name." Fields can be required (i.e., data must be entered), optional (i.e., can be left blank), or calculated (i.e., contain a value derived from a formula that is used on the data in other fields). A data item is a specific detail of an individual entity in a database. For example, the data element "state" may contain the names of any of the 50 states. The relationship between these database terms is shown in Figure 2.

Relational Databases

The most popular type of database is the relational database. In a relational database, data are stored in two-dimensional tables comprising rows and columns. The table (also called a relation or file) describes an entity. The rows are its records, and the columns are its fields or attributes. A relational database management system works with two data tables at the same time and relates the data through links (e.g., a common column or field).

Relational Database Characteristics

There are four general characteristics of a relation.

* First, each column contains a single value about the same attribute. So, for example, in Table 1, the first column in the table only contains the name of the student.

* Second, the order of the columns does not matter. In this example, the database management system would be able to process user queries just as easily if the order of the columns were ID number, street address, postal code, name, State, and City than in the current order.

* Third, the order of the rows in the relation does not matter. In this example, it is irrelevant to the database management system that the names in the first column of the table are not in alphabetical order.

* Finally, each row is unique. Although there are two John Smiths in the table, they are different individuals as signified by the different ID numbers and addresses.

Table 1: Sample Table for a Relational Database

Name ID Number Street Address City State Postal Code Smith, John 459671 124 Main Street Anywhere VA 22335 Seavers, Alice 213530 4587 Avenue A Hometown MD 18742 Jones, Millicent 140382 119 St. Jude Place Jerseyville CT 06899 Smith, John 220527 6403 Night Court Capitol City VA 22564 Azul, Joseph 777949 441 S. Taylor Avenue Springfield WA 80782

The structure for a relational database includes a unique name for the database and a description of the relations within the database. The relation is defined by its various data items, each of which has is given a specific name, type, and length. This gives the relational database a unique structure that differentiates it from other databases.

Terms & Concepts

Application Software: A software program that performs functions not related to the running of the computer itself. Application software includes word processing, electronic spreadsheets, computer graphics, and presentation software.

Attribute: A fact or characteristic about an entity in a database. For example, a database may house the name, address, and phone number (attributes) of the organization's employees (entity).

Data Item: A specific detail of an individual entity in a database. For example, the data element "year in school" may contain the items freshman, sophomore, junior, or senior. Database: A collection of data items used for multiple purposes which is stored on a computer.

Database Management System (DBMS): A software program that allows users to manage the data in a database. Database management systems are designed to increase the accessibility of data and the productivity of the user.

Enterprise: An organization that uses computers. Although this term is often applied to large organizations, the term can be applied to both small and large organizations.

Entity: A person, place, thing, event, or condition about which a database houses information. Entities in the database are described by various attributes.

Field: A column of data in a database file. For example, a database may contain the field "student name." Fields can be required (i.e., data must be entered), optional (i.e., can be left blank), or calculated (i.e., contain a value derived from a formula that is used on the data in other fields). A collection of fields is called a record.

Information System: A system that facilitates the flow of information and data between people or departments.

Information Technology (IT): The use of computers, communications networks, and knowledge in the creation, storage, and dispersal of data and information. Information technology comprises a wide range of items and abilities for use in the creation, storage, and distribution of information.

Personal Information Manager (PIM): A database management system that allows users to manage data to organize their personal activities, including managing contacts, calendars, schedules, and to-do lists, and storage, editing, and retrieval of notes and memos.

Processing: The activity of converting, analyzing, computing, and synthesizing data or information stored in a computer so that it is in a useful form.

Query: A search question used by a database management system to specify what data are to be retrieved from the database.

Record: A complete set of information about an entity. Records are composed of fields.

Relational Database: A database that stores data in two-dimensional tables. A relational database management system works with two data tables at the same time and relates the data through links (e.g., a common column or field).

Bibliography

Best, B. (2013). Are your documents under control?. Quality, 52, 40-42. Retrieved November 27, 2013 from EBSCO online database Business Source Premier. http:// search.ebscohost.com/login.aspx?direct=true&db=buh&AN=87522042

Elmasri, R., & Navathe, S. B. (1989). Fundamentals of database systems. Redwood City, CA: Benjamin/Cummings Publishing.

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Suggested Reading

Beyer, K., Cochrane, R., Hvizdos, M., Josifovski, V., Kleewein, J., Lapis, G., … Zhang, G. (2006). DB2 goes hybrid: Integrating native XML and XQuery with relational data and SQL. IBM Systems Journal, 45, 271-298. Retrieved August 1, 2007, from EBSCO Online Database Business Source Complete. http://search.ebscohost.com/ login.aspx?direct=true&db=bth&AN=21352284&site=ehost-live

Katircioglu, K., Brown, T. M., & Asghar, M. (2007). An SQL-based cost-effective inventory optimization solution. IBM Journal of Research & Development, 51(3/4), 433-445. Retrieved August 1, 2007, from EBSCO Online Database Business Source Complete. http://search.ebscohost.com/ login.aspx?direct=true&db=bth&AN=25732944&site=ehost-live

Kung, H.-J., & Tung, H.-L. (2006). An alternative approach to teaching database normalization: A simple algorithm and an interactive e-learning tool. Journal of Information Systems Education, 17, 315-325. Retrieved August 1, 2007, from EBSCO Online Database Business Source Complete. http://search.ebscohost.com/ login.aspx?direct=true&db=bth&AN=23435526&site=ehost-live

Stefanidis, K., Koutrika, G., & Pitoura, E. (2011). A survey on representation, composition and application of preferences in database systems. ACM Transactions on Database Systems, 36, 19-19.45. Retrieved November 27, 2013 from EBSCO online database Business Source Premier. http://search.ebscohost.com/login.aspx?direct=true&db=buh&AN=65287706

Tupper, C. (2011). Data architecture: From Zen to reality. Amsterdam, Netherlands: Morgan Kaufmann. Retrieved November 27, 2013 from EBSCO online database eBook Collection (EBSCOhost). http://search.ebscohost.com/ login.aspx?direct=true&db=nlebk&AN=363704&site=ehost-live