OP Scan index

version 1.5

OP Scan index (connectionID; tableID; fieldID; selectionSize; scanOrigin) Longint

Parameter	Type		Description
connectionID	Longint		Connection ID with target server
tableID	Longint		Number of the table in the database
fieldID	Longint		Number of the field in the table
selectionSize	Longint		New size for the target table's current selection
scanOrigin	Longint		Origin of scan (0 is end of index)
Function result	Longint		Error code result for the function

OP Scan index creates a new selection of selectionSize records for the table specified by taleID. OP Scan index returns a specific number of records from either the top or bottom of the index, depending on the specified direction.

fieldID must be an indexed field. fieldID must be a field from table tableID.

If selectionSize is greater than the number of records in tableID, all the records are selected.

If scanOrigin is less than 0, the records come from the end of the index. If scanOrigin is greater than or equal to 0, the records come from the beginning of the index.

If OP Scan index executes successfully, it returns 0. Otherwise, this function returns one of the following errors:

Error Code	Description
-9970	Field is not indexed.
-9971	Field number is out of range.
-9972	Table number is out of range.
10128	The 4D Open for 4th Dimension package has not been initialized.
10136	The connection does not exist.
10154	This command cannot be executed right now.

This example creates and prints a selection of this year's invoices out of the top 100 invoices.

   C_LONGINT(vRecords; $ErrCode)
   C_REAL(vValue;vMeanAmount)
   C_LONGINT(vTable;vFieldDate;vFieldAmount;vFromEnd)

   $errCode:=OP Get one field number (vConnectID;"[Invoices]Invoice date";vTable;vFieldDate)   
   $errCode:=OP Get one field number (vConnectID;"[Invoices]Invoice amount";vTable;vFieldAmount)
   
   ` Scan will be processed from end of index
   vFromEnd:= -1 
   ` Create a selection of the top 100 invoices
   $errCode := OP Scan index (vConnectID;vTable;vFieldAmount;100;vFromEnd)

   ` Compute this year's 1st of january
   vValue:="01/01/" + String ( Year of ( Current date ) ;"####") 
   ` Query for this year's invoices out of the top 100
   $errCode:=OP Single query selection (vConnectID;vTable;vFieldDate;">";->vValue;vRecords)

   PrintInvoices

OP All records, OP Reduce selection, OP Single order by, OP Single query, SCAN INDEX.