private decimal ToDecimal()
{
if (IsNull)
throw new SqlNullValueException();
if ((int)_data4 != 0 || _bScale > 28)
throw new OverflowException(SQLResource.s_conversionOverflowMessage);
return new decimal((int)_data1, (int)_data2, (int)_data3, !IsPositive, _bScale);
}