Fundamentals in Computer

Topics: SQL, Computer, Database management system Pages: 23 (6832 words) Published: September 14, 2013
database is a collection of data organized in a manner that allows access, retrieval, and use of that data. Data is a collection of unprocessed items, which can include text, numbers, images, audio, and video. Information is processed data; that is, it is organized, meaningful, and useful. With database software, often called a database management system (DBMS), users create a computerized database; add, modify, and delete data in the database; sort and retrieve data from the database; and create forms and reports from the data in the database. Data integrity identifies the quality of the data. An erroneous student address in a student database is an example of incorrect data. When a database contains this type of error, it loses integrity. Data integrity is very important because computers and people use information to make decisions and take actions.

Garbage in, garbage out (GIGO) is a computing phrase that points out the accuracy of a computer’s output depends on the accuracy of the input. If you enter incorrect data into a computer (garbage in), the computer will produce incorrect information (garbage out). QUALITIES OF VALUABLE INFOMRATION

• Accurate information is error free. Inaccurate information can lead to incorrect decisions. For example, consumers assume their credit report is accurate. If your credit report incorrectly shows past due payments, a bank may not lend you money for a car or house. • Verifiable information can be proven as correct or incorrect. For example, security personnel at an airport usually request some type of photo identification to verify that you are the person named on the ticket.

• Timely information has an age suited to its use. A decision to build additional schools in a particular district should be based on the most recent census report — not on one that is 20 years old. Most information loses its value with time. Some information, however, such as information about trends, gains value as time passes and more information is obtained. • Organized information is arranged to suit the needs and requirements of the decision maker. Different people may need the same information presented in a different manner. For example, an inventory manager may want an inventory report to list out-of-stock items first. The purchasing agent, instead, wants the report alphabetized by vendor. • Accessible information is available when the decision maker needs it. Having to wait for information may delay an important decision.

• Useful information has meaning to the person who receives it. Most information is important only to certain people or groups of people.
• Cost-effective information should give more value than it costs to produce. An organization occasionally should review the information it produces to determine if it still is cost-effective to produce. Sometimes, it is not easy to place a value on information. For this reason, some organizations create information only on demand, that is, as people request it, instead of on a regular basis. Many make information available online. Users then can access and print online information as they need it.

a database contains files (sometimes called tables), a file contains records, a record contains fields, and a field is made up of one or more characters bit is the smallest unit of data the computer can process. Eight bits grouped together in a unit comprise a byte. In the ASCII coding scheme, each byte represents a single character, which can be a number (4), letter (R), space, punctuation mark (?), or other symbol (&).

field is a combination of one or more related characters or bytes and is the smallest unit of data a user accesses. A field name uniquely identifies each field. When searching for data in a database, you often specify the field name. The field size defines the maximum number of characters a field can contain. The data type specifies

the kind of data a field can contain and how the field is used. Common data types...
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