///<summary>Toggles the value of a calculated column between the default value (if the row is detached) and the uncalculated value (if the row is attached).</summary>
///<remarks>This is called by each CalculatedColumn when the row is added to or removed from the table.</remarks>
internal void ToggleCalcColDefault(CalculatedColumn column)
{
values[column] = Table == null ? column.DefaultValue : CalculatedColumn.UncalculatedValue;
}
///<summary>Clears the current value from a calculated column, causing it to be recalculated next time the value is retrieved.</summary>
internal void InvalidateCalculatedValue(CalculatedColumn column)
{
values[column] = CalculatedColumn.UncalculatedValue;
RaiseValueChanged(column, oldValue: DBNull.Value); //Passing the old value would force unnecessary recalcs
}