//Door Joost
public static void getOmzetrapportage(ref Label label, DateTime from, DateTime to)
{
SomerenDB somerendb = new SomerenDB();
int aantalKlanten = somerendb.aantalKlanten(from, to);
int afzet = somerendb.afzet(from, to);
double omzet = somerendb.omzet(from, to);
label.Text = String.Format(
"aantal klanten : {0}\n" +
"afzet : {1}\n" +
"omzet: {2:C2}", aantalKlanten, afzet, omzet);
}