C5_SELECT

 SELECT
 Change the current work area
------------------------------------------------------------------------------
 Syntax

     SELECT <xnWorkArea> | <idAlias>

 Arguments

     <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.

 Description

     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
     database files.

 Notes

     .  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:

        SELECT Remote
        ? EOF()
        SELECT Main

        Using the aliased expression form, these statements become:

        ? Remote->(EOF())

     .  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.

 Examples

     .  This example opens a series of database files by SELECTing
        each work area by number then USEing each database file in that work
        area:

        SELECT 1
        USE Customer
        SELECT 2
        USE Invoices
        SELECT 3
        USE Parts
        SELECT Customer

     .  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

        SELECT Customer

     .  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
        is restored:

        nLastArea := SELECT()
        USE Newfile NEW
        //
        <statements>...
        //
        SELECT (nLastArea)

 Files   Library is CLIPPER.LIB.

See Also: ALIAS() EOF() SELECT() SET INDEX USE USED()



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2 responses to “C5_SELECT

  1. Pingback: DB Commands | Viva Clipper !

  2. Pingback: C5 Commands | Viva Clipper !

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