Database+Management+System+Software

media type="custom" key="4399651"  [|Database management system] **(DBMS)** - is software that allows a user to create and manage a computerized database. A DBMS also allows a user to create reports from stored data. In the PC market, Microsoft Access is the most widely used DBMS. Database keys, query tools, security elements, metadata, and backup and recovery utilities allow users to manipulate database data into information.

[|Database Keys]  [|Query Tools]To work with large amounts of data, database management systems come equipped with query tools that help users narrow down the amount of information that needs to be searched. A //query// allows users to ask questions designed to retrieve needed information. Requesting information involves the use of a query language. [|Structured Query Language] (SQL) is the most popular database query language. It is simple when compared with a programming language, but it is also "structured," meaning that it is not as freeform as natural programming languages that mimic human speech. The basic query command that SQL commands is the **Select command,** which asks a database to return records that match specified criteria. Information from one query can be used to pull up data from than one record source through a process called **joining,** which matches data frome fields in various record files. For example, if student names and grades were entered as separate records, "out of state" could be used as the primary key to find the grades of out-of-state students.
 * **Key** - attribute used to identify and provide a means to search database
 * **Primary key** - most important key in a field and //must be unique// (first names are a poor primary key; license plate numbers, phone, bank a[[image:j0254445.gif align="right"]] ccount, credit card, social security, reservation confirmation, and work order numbers are commonly used)
 * **Data browsing** - the process of moving through a database file, examining each record and looking for information //(used when a record's primary key is unknown)//

Security Measures A DBMS also provides security measures to protect and safequard data against theft, alteration, or deletion. Security methods include restricting access by requiring user identification and passwords.

[|Metadata and the Data Dictionary] Metadata is information about data. **Data dictionary** is the term for a body of metadata. Metadata can be used for many things, but often describes the significance of various elements of a database. Designers, users, and administrators use metadata to manage databases.

[|Legacy Database Access] A legacy database is a database that runs using languages, platforms, or models that are no longer supported by an organization's current database system. In order to be able to continue to access the information stored on these databases, their programming code must be made compatible with the new system. Another option for accessing legacy databases is to use software tools that allow the data to be read directly by newer database systems. These tools are often integrated into database management system software.

[|Backup and Recovery Utilities] Almost all companies keep sales, marketing, customer, payroll, and tax records on a database. To lose this data would be disastrous, so regular backups are made and stored safely. If a **recovery**, or restoration of data, is needed, the most recent backup is used. Important backup information is often stored in safes or off-site.