Database Management Software

Databases are software applications designed to store and retrieve information. Databases have long been employed as a vital tool by government and business to store, organize, and locate information. Modern database management systems are complex software applications that combine information from discrete sources, allowing information to be quickly located and displayed to the user. Perhaps the most elementary example of a database is a simple list of names and their associated phone numbers.

Databases are used for problem solving by all types and sizes of organizations, as well as by consumers, often also referred to as end users. Businesses commonly employ electronic databases to store and retrieve lists of customer names, addresses, phone numbers, billing information, and other data valuable to the organization. Databases are used to solve problems and to answer important questions, such as how much money the company owed, to whom, and to flag when the account becomes past due for payment. They can be also used for data mining to query large knowledge bases, making them vital in helping organizations achieve financial goals, increase customer satisfaction as well as efficiency, and reap profits.

With the advent of the personal computer, database software has become standard in business, government, and even private individuals' work to store, sort, and retrieve information. The Internet has proven to be a valuable backbone for allowing users to access vast databases from remote locations using a personal computer equipped with a modem and communication software. Business and government organizations rely on computer networks and the Internet to distribute databases to their workers and customers. Consumers utilize stand-alone personal computers to create and access databases to store and retrieve information. Common consumer database applications include storing lists of names, addresses, phone numbers, recipes, videos, compact discs (CDs), digital versatile discs (DVDs), etc. Databases can be used to store a wide variety of information in various formats and can also be used to store and retrieve graphics, sounds, text, or a mixture of these formats.

Database Structure

Databases are computer files that store information. These data can be of many different types and formats, depending on the mission. All databases store data in tables or groups of tables. Each table consists of rows and columns, not unlike a grid or graph. Vertical columns of a table are called fields, and the horizontal rows are called records. Each field has a label at the top, and each record has a number at the left margin. An example of a table with two fields and three records follows. The fields are "name," and "phone number."

Relational Databases

When two or more tables are related in a database, it is known as a " relational database. " Relational databases allow records from more than one table to be searched and displayed. The two or more tables must share a common field, like name, phone number, etc. If two tables contain a field that is common to both tables, then the data from two tables can be searched in a single query.

SQL

SQL stands for Structured Query Language and is becoming the standard dialect for accessing database management systems. SQL permits users to perform a wide variety of functions, including creating databases, adding information, updating or altering information stored in the database, deleting data, searching for specific information, and displaying that information once it has been located by a query. SQL can be utilized to search more than one table at a time and can then construct new tables of information. SQL also permits users to change the structure of an existing database and to modify security settings.

SQL command statements are entered via the keyboard and are executed like a software program. Assume that a company has a database table called "employees." This table contains the complete list of all employees with their name, address, city, and phone number. If a list is needed of all the names and phone numbers in this table, one would write the SQL statement as follows:

Select FirstName, LastName, Phone

From EmployeeTable;

The preceding statement tells the database to display all the entries in the table because no specific search condition is specified. If the scope of the search is limited to employees living in a specific city, then one would write the following SQL statement using the Where command.

Select FirstName, LastName, Phone

From EmployeeTable

Where City "Boston";

Commercial Database Products

There are numerous database development software packages on the market, and they meet a wide variety of end user and commercial applications. These packages support a wide variety of operating systems and computer platforms, including Windows, Macintosh, Linux, and others. Each is intended either for commercial or consumer applications.

Microsoft produces the Access database development software. This package runs under the Windows operating system and is intended for both business and consumer applications. It also offers SQL Server for large database projects. Oracle is a database development software package for creating powerful applications for large-scale database applications in sizable organizations and government agencies. File Maker Pro is a Macintosh-based database development package for commercial and consumer sized applications.

Security

The security and integrity of information systems is of vast importance to organizations, and significant resources are often deployed in this area. The overall integrity and security of the database is the joint responsibility of the network administrator and the database administrator.

If the database resides on a network, which is typical, network security is the first line of defense to protect the database and the information stored within it. Network administrators can limit access to the directory or files where the actual data and program files are stored. This denies access to those who would delete, modify, or corrupt these files.

Working in concert with the network administrator, the database administrator is responsible for ensuring that the database system is secure from unauthorized use and access. Additional responsibilities include modifying the database and upgrading or maintaining the system. The database administrator secures the database application by applying the security settings offered by the particular database package to prevent unauthorized access. The administrator accomplishes this by assigning user names and passwords to everyone in the organization.

Such a system forces users to log onto the system with a valid user name and password before gaining access. The user name and password tell the database software what type of access to grant to the user. This prevents data stored in the database from being altered, deleted, or copied without permission. Access rights are arranged in a hierarchy, with some users having limited access, while trusted users have expanded access. Groups of users can be confined to a "read only" mode that allows them to read information stored in the database but prevents them from making any alterations.

Database management software systems have created the ability to store and retrieve large quantities of information. They have allowed data from widely dissimilar sources to be correlated in order to solve problems and answer questions. They allow companies to maintain lists of their customers, suppliers, inventory, financial records, trade secrets, and other valuable information. Databases can be used to store and retrieve information in many different formats: graphics, sound, text, and mixed modes. The Structured Query Language (SQL) allows databases to be created, populated, updated, and searched. Database management systems can be accessed using stand-alone computers, office networks, and the global Internet, and are undergoing constant evolution and expansion.

see also Computer Supported Cooperative Work (CSCW); Productivity Software; SQL; SQL: Databases.

Joseph J. Lazzaro

Bibliography

Ramakrishnan, Raghu, and Johannes Gehrke. Database Management Systems, 2nd ed. Boston: McGraw-Hill, 2000.

McFadden, Fred R., Jeffrey A. Hoffer, and Mary B. Prescott. Modern Database Management, 6th ed. Upper Saddle River, NJ: Prentice Hall, 2001.