在给定时间段内选择状态历史表的活动状态

I have a simple table containing a history of states of a 'reader' object. The state can be ACTIVE or INACTIVE. Now I would like to have a query, which picks all readers, which were ACTIVE in a given period. The following image shows what I mean: The 'readers' with the green 'lifeline' were ACTIVE in the displayed period; so they shall be returned in the query.I have a simple table containing a history of s