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harbour-core/harbour/doc/en/rdd.txt
2000-04-11 23:23:28 +00:00

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/*
* $Id$
*/
/*
* The following parts are Copyright of the individual authors.
* www - http://www.harbour-project.org
*
* Copyright 1999 Luiz Rafael Culik <culik@sl.conex.net>
* DB*() documentation
* ORD*() documentation
* RDD*() documentation
*
* See doc/license.txt for licensing terms.
*
*/
/* $DOC$
* $FUNCNAME$
* RDDLIST()
* $CATEGORY$
* Database
* $ONELINER$
* Return an array of the available Replaceable Database Drivers
* $SYNTAX$
* RDDLIST([<nRDDType>]) --> aRDDList
* $ARGUMENTS$
* <nRDDType> is an integer that represents the type of the RDD you
* wish to list. The constants RDT_FULL and RDT_TRANSFER represent the two
* types of RDDs currently available.
*
* RDDType Summary
* ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
* Constant Value Meaning
* ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
* RDT_FULL 1 Full RDD implementation
* RDT_TRANSFER 2 Import/Export only driver
* ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ
*
* RDT_FULL identifies full-featured RDDs that have all the capabilities
* associated with an RDD.
*
* RDT_TRANSFER identifies RDDs of limited capability. They can only
* transfer records between files. You cannot use these limited RDD
* drivers to open a file in a work area. The SDF and DELIM drivers are
* examples of this type of RDD. They are only used in the implementation
* of APPEND FROM and COPY TO with SDF or DELIMITED files.
* $RETURNS$
* RDDLIST() returns a one-dimensional array of the RDD names registered
* with the application as <nRDDType>.
* $DESCRIPTION$
* RDDLIST() is an RDD function that returns a one-dimensional array that
* lists the available RDDs.
*
* If you do not supply <nRDDType>, all available RDDs, regardless of type,
* are returned.
* $EXAMPLES$
* In this example RDDLIST() returns an array containing the
* character strings, "DBF", "SDF", "DELIM", "DBFCDX", and "DBFNTX":
*
* REQUEST DBFCDX
*
* .
* . < statements >
* .
*
* aRDDs := RDDLIST()
*
* // Returns {"DBF", SDF", "DELIM", "DBFCDX", "DBFNTX" }
*
* In this example, RDDLIST() returns an array containing the
* character strings, "SDF" and "DELIM":
*
* #include "rddsys.ch"
* .
* . < statements >
* .
* aImpExp := RDDLIST( RDT TRANSFER )
*
* $TESTS$
*
* $STATUS$
* R
* $COMPLIANCE$
*
* $SEEALSO$
*
* $INCLUDE$
* RDDSYS.CH
* $END$
*/
/* $DOC$
* $FUNCNAME$
* RDDNAME()
* $CATEGORY$
* Database
* $ONELINER$
* Return the name of the currently active RDD
* $SYNTAX$
* RDDNAME() --> cRDDName
* $ARGUMENTS$
*
* $RETURNS$
* Returns a character string, cRDDName, the registered name of the active
* RDD in the current or specified work area.
* $DESCRIPTION$
* RDDNAME() is an RDD function that returns a character string, cRDDName,
* the name of the active RDD in the current or specified work area.
*
* You can specify a work area other than the currently active work area by
* aliasing the function.
* $EXAMPLES$
* USE Customer VIA "DBFNTX" NEW
* USE Sales VIA "DBFCDX" NEW
*
* ? RDDNAME() // Returns: DBFCDX
* ? Customer->( RDDNAME() ) // Returns: DBFNTX
* ? Sales->( RDDNAME() ) // Returns: DBFCDX
* $TESTS$
*
* $STATUS$
* R
* $COMPLIANCE$
*
* $SEEALSO$
* RDDLIST()
* $INCLUDE$
*
* $END$
*/
/* $DOC$
* $FUNCNAME$
* RDDSETDEFAULT()
* $CATEGORY$
* Database
* $ONELINER$
* Set or return the default RDD for the application
* $SYNTAX$
* RDDSETDEFAULT([<cNewDefaultRDD>])
* --> cPreviousDefaultRDD
*
* $ARGUMENTS$
* <cNewDefaultRDD> is a character string, the name of the RDD that is
* to be made the new default RDD in the application.
* $RETURNS$
* RDDSETDEFAULT() returns a character string, cPreviousDefaultRDD, the
* name of the previous default driver. The default driver is the driver
* that HARBOUR uses if you do not explicitly specify an RDD with the
* VIA clause of the USE command.
* $DESCRIPTION$
* RDDSETDEFAULT() is an RDD function that sets or returns the name of the
* previous default RDD driver and, optionally, sets the current driver to
* the new RDD driver specified by cNewDefaultRDD. If <cNewDefaultDriver>
* is not specified, the current default driver name is returned and
* continues to be the current default driver.
*
* This function replaces the DBSETDRIVER() function.
* $EXAMPLES$
* // If the default driver is not DBFNTX, make it the default
*
* IF ( RDDSETDEFAULT() != "DBFNTX" )
* cOldRdd := RDDSETDEFAULT( "DBFNTX" )
* ENDIF
* $TESTS$
*
* $STATUS$
* R
* $COMPLIANCE$
*
* $SEEALSO$
* DBSETDRIVER()
* $INCLUDE$
*
* $END$
*/
/* $DOC$
* $FUNCNAME$
* __RDDSETDEFAULT()
* $CATEGORY$
* Database
* $ONELINER$
* Set or return the default RDD for the application
* $SYNTAX$
* __RDDSETDEFAULT([<cNewDefaultRDD>])
* --> cPreviousDefaultRDD
*
* $ARGUMENTS$
* <cNewDefaultRDD> is a character string, the name of the RDD that is
* to be made the new default RDD in the application.
* $RETURNS$
* __RDDSETDEFAULT() returns a character string, cPreviousDefaultRDD, the
* name of the previous default driver. The default driver is the driver
* that HARBOUR uses if you do not explicitly specify an RDD with the
* VIA clause of the USE command.
* $DESCRIPTION$
* RDDSETDEFAULT() is an RDD function that sets or returns the name of the
* previous default RDD driver and, optionally, sets the current driver to
* the new RDD driver specified by cNewDefaultRDD. If <cNewDefaultDriver>
* is not specified, the current default driver name is returned and
* continues to be the current default driver.
*
* This function replaces the DBSETDRIVER() function.
* $EXAMPLES$
* // If the default driver is not DBFNTX, make it the default
*
* IF ( __RDDSETDEFAULT() != "DBFNTX" )
* cOldRdd := __RDDSETDEFAULT( "DBFNTX" )
* ENDIF
* $TESTS$
*
* $STATUS$
* R
* $COMPLIANCE$
*
* $SEEALSO$
* DBSETDRIVER()
* $INCLUDE$
*
* $END$
*/