How to use single inheritance in propel schema

Question

I need to make a 'Event' class and propel schema with Columns:

id
employee_id
date_start
date_end
type

How to implement the simple inheritance based on the type column.

All classes should extend the abstract Event class.

Initial sub-class: JoinEvent

can anyone write a schema for it?

I have written schema but not sure whether it is correct or not.

<table name="event" phpName="Event">
        <column name="id"          type="integer" required="true" primaryKey="true" autoIncrement="true" />
        <column name="employee_id" type="integer" required="true" />
        <column name="date_start"  type="date"  required="true" />
        <column name="date_end"    type="date"  required="false" />
        <column name="type"        type="integer" inheritance="single">
            <inheritance key="1" class="JoinEvent" extends="Event"/>
        </column>
        <foreign-key foreignTable="employee" name="FI_event_employee">
            <reference local="employee_id" foreign="id" />
        </foreign-key>
    </table>

Please help me.