Learning Visually with Examples [Electronic resources]

Raul F. Chong, Clara Liu, Sylvia F. Qi, Dwaine R. Snow

نسخه متنی -صفحه : 312/ 280
نمايش فراداده

V

value

(1) The alpha or numeric content of a field or variable.

(2) The smallest unit of data manipulated in SQL.

(3) A specific data item at the intersection of a column and a row.

variable

A data element that specifies a value that can be changed.

variable-length string

A character, graphic, or binary string whose length is not fixed but can range within set limits. Also referred to as a

varying length string .

version recovery

The restoration of a previous version of the database, using an image that was created during a backup operation.

view

(1) A logical table that consists of data generated by a query. A view is based on an underlying set of base tables, and the data in a view is determined by a

SELECT statement that is run on the base tables. Contrast with

base table .

(2) A way of looking at the information about or contained in objects. Each view might reveal different information about its objects.

Visual Explain

A tool that provides a graphical interface for database administrators and application programmers to display and analyze detailed information on the access plan of a given SQL statement. The tasks provided by this tool can be accessed from the Control Center.

volatile table

A table for which SQL operations choose index access whenever possible.