I am working on a project where I have a Reminders API.
My entities are made of two important properties : Frequency and Type.

Here is the base classes :

public abstract class ReminderDao
{
    public int Id { get; set; }

    public abstract ReminderFrequency Frequency { get; }
    public abstract ReminderType Type { get; }

    public string Title { get; set; }
    public string Description { get; set; }
}

public abstract class OneTimeReminderDao : ReminderDao
{
    public override ReminderFrequency Frequency => ReminderFrequency.OneTime;

    // OneTime
    public DateTimeOffset Date { get; set; }
}

public abstract class RecurringReminderDao : ReminderDao
{
    public override ReminderFrequency Frequency => ReminderFrequency.Recurring;

    // Recurring
    public DateTimeOffset StartDate { get; set; }
    public TimeSpan Interval { get; set; }
}

Here is the implementations:

public sealed class AppointmentOneTimeReminderDao : OneTimeReminderDao
{
    public override ReminderType Type => ReminderType.Appointment;
}

public sealed class AppointmentRecurringReminderDao : RecurringReminderDao
{
    public override ReminderType Type => ReminderType.Appointment;
}

I am stuck because I don’t know how to make a good TPH inheritance in order to get in a same table Reminders the one time and the recurring reminders with typed reminders.

I am taking any advice ! Thanks a lot !