Difference between revisions of "SELECT"

Revision as of 09:59, 4 June 2009

Class

Table Basics

Purpose

Select a workarea

Syntax

SELECT <workarea | alias>

See Also

ALIAS(), DB_MAXWKA, SELECT(), SET FILTER, SET RELATION, SET VIEW, USE, WORKAREA()

Description

The SELECT command is used to select a workarea. By default Recital environments have 20 workareas. At any given time, a particular workarea is active and selected. The number of workareas may be configured up to the maximum supported by setting the environment variable / symbol DB_MAXWKA.

The workareas are numbered 1 to 20 (or DB_MAXWKA) and can be selected by number. When you USE a table in a selected workarea, an ALIAS name may be optionally specified. If none is specified, the table basename can also be used as the alias as can the workarea letter A to T (up to Z if DB_MAXWKA is set higher). The alias 'm' is reserved for memory variables and cannot be used to reference a workarea. This ALIAS name gives the workarea an identification, so that you can reference fields in workareas other than the currently selected one, by preceding the field name with the ALIAS name followed by '->' or '.' followed by the field name. This construction is known as an alias pointer.

Each workarea contains the context for the table that has been opened in that workarea. The current record pointer, the current record, the format file, the index files, the filter condition, and the relationships to other workareas. The SELECT 0 command selects the next available workarea and provides an alternative to using the WORKAREA() function. The LIST STATUS command provides full details of the current status of each workarea.

Example

select a
use patrons index events, dates alias pat
select b
use addresses index addr_names alias add
select pat
? add.state

Products

Recital Database Server, Recital Mirage Server, Recital Terminal Developer