Reference no: EM131395143

What Functions Are Common to Most Database Management Systems? Database management systems (DBMSs) are available for many sizes and types of computers. Whether designed for a small or large computer, most DBMSs perform common functions. A data dictionary, sometimes called a repository, contains data about each fi le in the database and each field in those fi les. A DBMS offers several methods to retrieve and maintain data in the database, such as query languages, query by example, forms, and report generators. A query language consists of simple, English-like statements that allow users to specify the data to display, print, or store. Query by example (QBE) has a graphical user interface that assists users with retrieving data. A form, sometimes called a data entry form, is a window on the screen that provides areas for entering or modifying data in a database. A report generator, also called a report writer, allows users to design a report on the screen, retrieve data into the report design, and then display or print the report. To supply security, most DBMSs can identify different levels of access privileges that define the actions a specific user or group of users can perform for each fi eld in a database. If a database is damaged or destroyed, a DBMS provides techniques to return the database to a usable form. A backup is a copy of the database. A log is a listing of activities that modify the contents of the database. A recovery utility uses the logs and/or backups to restore the database using roll forward or rollback techniques. In a roll forward, also called forward recovery, the DBMS uses the log to reenter changes made to the database since the last save or backup. In a rollback, also called backward recovery, the DBMS uses the log to undo any changes made to the database during a certain period. Continuous backup is a backup plan in which all data is backed up whenever a change is made.