[About The Guide]
Change the current work area
SELECT <xnWorkArea> | <idAlias>
<xnWorkArea> is the work area number between 0 and 250 inclusive.
This argument is an extended expression and can be specified either as a
literal number or as a numeric expression enclosed in parentheses.
<idAlias> is the name of an existing work area to SELECT if there is
a database file open in that area.
SELECT is a database command that changes work areas. CA-Clipper
supports 250 work areas, with each work area a logical handle to an open
database file and all of its attributes. You can refer to work areas
with SELECT by number or by alias. The alias of a work area is
automatically assigned when a database file is USEd in that work area or
by using the ALIAS clause.
Work area 0 refers to the first empty or next available work area.
Using this, you can SELECT 0 and USE <xcDatabase> as a method of opening
. Aliased expressions: Aliased expressions are a much more
powerful method of selecting new work areas than the SELECT command.
Instead of SELECTing a work area, and then performing an operation
for that work area, you can apply an alias to an expression that
performs the operation. This is done by specifying the alias of the
remote work area and the expression enclosed in parentheses. For
example, to access the value of EOF() in an unselected work area, you
would normally execute a series of statements like the following:
Using the aliased expression form, these statements become:
. USE...NEW: Instead of using SELECT0 and USE <xcDatabase> to
open a database file in a new work area, the preferred method is to
USE <xcDatabase> NEW.
. This example opens a series of database files by SELECTing
each work area by number then USEing each database file in that work
. A better method is to open each database in the next available
work area by specifying the NEW clause on the USE command line. In
this example USE...NEW is employed instead of SELECT0 and then USE:
USE Customer NEW
USE Invoices NEW
. This code fragment changes work areas while saving the current
work area name to a variable using the SELECT() function. After
executing an operation for the new work area, the original work area
nLastArea := SELECT()
USE Newfile NEW
Files Library is CLIPPER.LIB.
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