Here are a couple of examples of how to retrieve and update a nullable db column of datetime datatype using LLBLGen Pro and present the editable/nullable value within a NullableDateTimePicker object.
// retrieving nullable Date from DB to NullableDateTimePicker **************************************************************************
PaymentEntity oPayment = new PaymentEntity(iPaymentID);
if (oPayment.CheckDate > dtpCheckDate.MinDate && oPayment.CheckDate < dtpCheckDate.MaxDate)
{
dtpCheckDate.Checked = true;
dtpCheckDate.Value = oPayment.CheckDate;
}
else
dtpCheckDate.Checked = false;
// updating nullable Date from NullableDateTimePicker to DB **************************************************************************
PaymentEntity oPayment = new PaymentEntity(iPaymentID);
if (dtpCheckDate.Value == DBNull.Value)
oPayment.SetNewFieldValue("CheckDate", null);
else
oPayment.CheckDate = (DateTime)dtpCheckDate.Value;
oPayment.Save();