public void IncreaseDefaultDate()
{
DataManager dataManager = new DataManager(connectionString);
DateTime oldDate = DateTime.MinValue;
DateTime newDefaultDate;
string pawnID = TransIDTextBox.Text;
for (int i = 0; i < pawnInfoData.Rows.Count; i++)
{
oldDate = Convert.ToDateTime(pawnInfoData.Rows[i]["DefaultDate"]);
}
newDefaultDate = oldDate.AddDays(30);
dataManager.UpdateDefaultDate(pawnID, newDefaultDate.ToString());
}