The QTD is the output. and NOTA a local variable.
Why this not sucess?
My table DIARIO_PROVA_ALUNO has severals registers.


begin
QTD = 0;
FOR SELECT NOTA_PROVA FROM DIARIO_PROVA_ALUNO INTO :NOTA
DO
BEGIN
QTD = QTD+NOTA;
END
suspend;
end