Tag Archives: INDEXKEY()
Harbour Index / Order System Functions
IndexOrd()
INDEXORD()
Returns the numeric position of the controlling index.
Syntax
INDEXORD() --> <nPosition>
Arguments
None.
Returns
<nPosition> Ordinal position of a controling index
Description
The INDEXORD() function returns the numeric position of the current controlling index in the selected or designated work area. A returned value of 0 indicated that no active index is controlling the database, which therefore is in the natural order.
Examples
USE tests NEW INDEX test1
IF INDEXORD() > 0
? "Current order is", INDEXORD()
ENDIF
Compliance
Clipper
Platforms
All
Files
Library is rdd
Seealso
INDEXKEY()
IndexExt()
INDEXEXT()
Returns the file extension of the index module used in an application
Syntax
INDEXEXT() --> <cExtension>
Arguments
None.
Returns
<cExtension> Current driver file extension
Description
This function returns a string that tells what indexes are to be used or will be created in the compiled application. The default value is “.ntx”. This is controled by the particular database driver that is linked with the application.
Examples
IF INDEXEXT() == ".ntx"
? "Current driver being used is DBFNTX"
ENDIF
Compliance
Clipper
Platforms
All
Files
Library is rdd
Seealso
INDEXKEY(), INDEXORD()
C5_INDEXKEY
INDEXKEY()
Return the key expression of a specified index
------------------------------------------------------------------------------
Syntax
INDEXKEY(<nOrder>) --> cKeyExp
Arguments
<nOrder> is the ordinal position of the index in the list of index
files opened by the last USE...INDEX or SET INDEX TO command for the
current work area. A zero value specifies the controlling index,
without regard to its actual position in the list.
Returns
INDEXKEY() returns the key expression of the specified index as a
character string. If there is no corresponding index or if no database
file is open, INDEXKEY() returns a null string ("").
Description
INDEXKEY() is a database function that determines the key expression of
a specified index in the current work area and returns it as a character
string. To evaluate the key expression, specify INDEXKEY() as a macro
expression like this: &(INDEXKEY(<nOrder>)).
INDEXKEY() has a number of applications, but two specific instances are
important. Using INDEXKEY(), you can TOTAL on the key expression of the
controlling index without having to specify the key expression in the
source code. The other instance occurs within a DBEDIT() user function.
Here, you may want to determine whether or not to update the screen
after the user has edited a record. Generally, it is only necessary to
update the screen if the key expression of the controlling index has
changed for the current record. Both of these examples are illustrated
below.
By default, INDEXKEY() operates on the currently selected work area. It
can be made to operate on an unselected work area by specifying it
within an aliased expression (see example below).
Examples
. This example accesses the key expression of open indexes in
the current work area:
#define ORD_NATURAL 0
#define ORD_NAME 1
#define ORD_SERIAL 2
//
USE Customer INDEX Name, Serial NEW
SET ORDER TO ORD_SERIAL
? INDEXKEY(ORD_NAME) // Result: Name index exp
? INDEXKEY(ORD_SERIAL) // Result: Serial index exp
? INDEXKEY(ORD_NATURAL) // Result: Serial index exp
. This example accesses the key expression of the controlling
index in an unselected work area:
USE Customer INDEX Name, Serial NEW
USE Sales INDEX Salesman NEW
? INDEXKEY(0), Customer->(INDEXKEY(0))
. This example uses INDEXKEY() as part of a TOTAL ON key
expression. Notice that INDEXKEY() is specified using a macro
expression to force evaluation of the expression:
USE Sales INDEX Salesman NEW
TOTAL ON &(INDEXKEY(0)) FIELDS SaleAmount TO ;
SalesSummary
. This example uses INDEXKEY() to determine whether the DBEDIT()
screen should be updated after the user has edited the current field
value. Generally, you must update the DBEDIT() screen if the user
changes a field that is part of the controlling index key.
FieldEdit() is a user-defined function called from a DBEDIT() user
function to edit the current field if the user has pressed an edit
key.
#include "Dbedit.ch"
#define ORD_NATURAL 0
FUNCTION FieldEdit()
LOCAL indexVal
// Save current key expression and value
indexVal = &(INDEXKEY(ORD_NATURAL))
.
. <code to GET current field value>
.
// Refresh screen if key value has changed
IF indexVal != &(INDEXKEY(ORD_NATURAL))
nRequest = DE_REFRESH
ELSE
nRequest = DE_CONT
ENDIF
RETURN nRequest
Files Library is CLIPPER.LIB.
See Also: INDEX INDEXEXT() INDEXORD() SET INDEX SET ORDER
C5 Index Commands and Functions
Index Commands and Functions
Commands :
DELETE TAG :
Delete a Tag
DELETE TAG <cOrderName> [IN <xcOrderBagName>]
[, <cOrderName> [IN xcOrderBagName] list>]
INDEX ON … :
Create an index file
INDEX ON <expKey>
[TAG <cOrderName>]
TO <xcOrderBagName>
[FOR <lCondition>] [ALL]
[WHILE <lCondition>]
[NEXT <nNumber>]
[RECORD <nRecord>]
[REST]
[EVAL <bBlock>
[EVERY <nInterval>]
[UNIQUE]
[ASCENDING|DESCENDING]
REINDEX :
Rebuild open indexes in the current workarea
REINDEX
[EVAL <lCondition>]
[EVERY <nRecords>]]
SET INDEX :
Open index file(s) in the current work area
SET INDEX TO [<xcIndex list>]
SET ORDER :
Set a new controlling index
SET ORDER TO [<nOrder> | [TAG <cOrderName>]
[IN <xcOrderBagName>]]>
SET UNIQUE* :
Toggle the inclusion of nonunique keys into an index
SET UNIQUE on | OFF | <xlToggle>
Functions :
DBCLEARINDEX() :
Close all indexes for the current work area
DBCLEARINDEX() --> NIL
DBCREATEINDEX() :
Create an index file
DBCREATEINDEX( <cIndexName>, <cKeyExpr>,
<bKeyExpr>,
[<lUnique>] ) --> NIL
DBREINDEX() :
Recreate all active indexes for the current work area
DBREINDEX() --> NIL
DBSEEK() :
Move to the record having the specified key value
DBSEEK( <expKey>, [<lSoftSeek>] ) --> lFound
DBSETINDEX() :
Open an index for the current work area
DBSETINDEX( <cIndexName> ) --> NIL DBSETINDEX( <cOrderBagName> ) --> NIL
DBSETORDER() :
Set the controlling order for the current work area
DBSETORDER( <nOrderNum> ) --> NIL
DESCEND() :
Return a descending index key value
DESCEND( <exp> ) --> ValueInverted
FOUND() :
Determine if the previous search operation succeeded
FOUND() --> lSuccess
INDEXEXT() :
Return the default index extension
INDEXEXT() --> cExtension
INDEXKEY() :
Return the key expression of a specified index
INDEXKEY( <nOrder> ) --> cKeyExp
INDEXORD() :
Return the order position of the controlling index
INDEXORD() --> nOrder
ORDBAGEXT() :
Return the default Order Bag RDD extension
ORDBAGEXT() --> cBagExt
ORDBAGNAME() :
Return the Order Bag name of a specific Order
ORDBAGNAME(<nOrder> | <cOrderName>) --> cOrderBagName
ORDCOND()
Specify conditions for ordering
ORDCOND([FOR <lCondition>]
[ALL] [WHILE <;lCondition>]
[EVAL <bBlock> [EVERY <nInterval>]]
[RECORD <nRecord>] [NEXT <nNumber>]
[REST] [DESCENDING])
ORDCONDSET()
Set the condition and scope for an order
ORDCONDSET([<cForCondition>],
[<bForCondition>],
[<lAll>],
[<bWhileCondition>],
[<bEval>],
[<nInterval>],
[<nStart>],
[<nNext>],
[<nRecord>],
[<lRest>],
[<lDescend>],
[<lAdditive>],
[<lCurrent>],
[<lCustom>],
[<lNoOptimize>]) --> lSuccess
ORDCREATE():
Create an Order in an Order Bag
ORDCREATE(<cOrderBagName>,[<cOrderName>], <cExpKey>,
[<bExpKey>], [<lUnique>]) --> NIL
ORDDESCEND()
Return and optionally change the descending flag of an order
ORDDESCEND([<cOrder> | <nPosition>],[<cIndexFile>],
[<lNewDescend>]) --> lCurrentDescend
ORDDESTROY() :
Remove a specified Order from an Order Bag
ORDDESTROY(<cOrderName> [, <cOrderBagName> ]) --> NIL
ORDFOR() :
Return the FOR expression of an Order
ORDFOR(<cOrderName> | <nOrder>
[, <cOrderBagName>]) --> cForExp
ORDISUNIQUE()
Return the status of the unique flag for a given order
ORDISUNIQUE([<cOrder> | <nPosition>],
[<cIndexFile>]) --> lUnique
ORDKEY() :
Return the Key expression of an Order
ORDKEY(<cOrderName> | <nOrder> [, <cOrderBagName>]) --> cExpKey
ORDKEYADD()
Add a key to a custom built order
ORDKEYADD([<cOrder> | <nPosition>],
[<cIndexFile>],[<expKeyValue>]) --> lSuccess
ORDKEYCOUNT()
Return the number of keys in an order
ORDKEYCOUNT([<cOrder> | <nPosition>],
[<cIndexFile>]) --> nKeys
ORDKEYDEL()
Delete a key from a custom built order
ORDKEYDEL([<cOrder> | <nPosition>],
[<cIndexFile>],
[<expKeyValue>]) --> lSuccess
ORDKEYGOTO()
Move to a record specified by its logical record number
ORDKEYGOTO(<nKeyNo>) --> lSuccess
ORDKEYNO()
Get the logical record number of the current record
ORDKEYNO([<cOrder> | <nPosition>],
[<cIndexFile>]) --> nKeyNo
ORDKEYVAL()
Get key value of the current record from controlling order
ORDKEYVAL() --> xKeyValue
ORDLISTADD() :
Add Order Bag contents or single Order to the Order List
ORDLISTADD(<cOrderBagName>
[, <cOrderName>]) --> NIL
ORDLISTCLEAR() :
Clear the current Order List
ORDLISTCLEAR() --> NIL
ORDLISTREBUILD() :
Rebuild all Orders in the Order List of the current work area
ORDLISTREBUILD() --> NIL
ORDNAME() :
Return the name of an Order in the work area
ORDNAME(<nOrder>[,<cOrderBagName>])
--> cOrderName
ORDNUMBER() :
Return the position of an Order in the current Order List
ORDNUMBER(<cOrderName>[, <cOrderBagName>]) --> nOrderNo
ORDSCOPE()
Set or clear the boundaries for scoping key values
ORDSCOPE(<nScope>, [<expNewValue>]) --> uCurrentValue
ORDSETFOCUS() :
Set focus to an Order in an Order List
ORDSETFOCUS([<cOrderName> | <nOrder>]
[,<cOrderBagName>]) --> cPrevOrderNameInFocus
ORDSETRELAT()
Relate a specified work area to the current work area
ORDSETRELATION(<nArea> | <cAlias>,<bKey>, [<cKey>])
--> NIL
ORDSKIPUNIQUE()
Move record pointer to the next or previous unique key
ORDSKIPUNIQUE([<nDirection>]) –> lSuccess
