query1.SQL.Clear;
query1.sql.text:= 'Select max(ctrlconcepto) as maximo from cobranzas where alucurso = :uno and concepto = :dos';
Query1.Params[0].Value:= IntToStr( x );
Query1.Params[1].Value:= dbedit9.text;
query1.Active:=true;
max:= Query1.Fields[0].Value;