QMClearselect

The QMClearSelect function clears a select list. It is analogous to the QMBasic CLEARSELECT statement.

The QMClearSelect function clears the specified select list. No error occurs if the list was not active.

Applications that use select list 0 (the default select list) and could leave unprocessed items in the list should always clear it to avoid unwanted effects on later server processing.

QMSelect fClients, 1

Id = QMReadNext(1, ErrNo)

If ErrNo <> 0 Then Exit Do

Rec = QMRead(fClients, Id, ErrNo)

If QMExtract(Rec, 1, 0, 0) = "" Then Exit Do

Loop

QMClearSelect 1

QMSelect(fClients, 1);

do {

Id = QMReadNext(1);

if (Id == NULL) break;

Rec = QMRead(fClients, Id, ErrNo);

QMFree(Id);

Fld = QMExtract(Rec, 1, 0, 0);

if (Fld == NULL) break;

QMFree(Rec);

QMFree(Fld);

} while(1);

QMClearSelect(1);

QMBasic

session->Select(fClients, 1)

loop

Id = session->ReadNext(1)

until Id = ""

Rec = session->Read(fClients, Id, ErrNo)

until Rec<1> = ""

repeat

session->ClearSelect(1)

The above program fragment builds select list 1 and uses it to process records from the file open as fClients. It exits from the loop when it finds the first record where field 1 is empty. Because this will leave a partially processed select list, QMClearSelect is used to clear the list.

Note that the C example leaves variables Rec and Fld pointing to dynamically allocated memory areas on exit from the loop. These must be released using QMFree() when they are no longer needed.