facebook - FQL 使用 uid 条件查询 event_member 表时获取空数组

Question

当我执行以下 FQL 查询时

SELECT uid, rsvp_status FROM event_member WHERE uid = me()

我得到一份我正在参加的活动的清单。当我执行以下任一 FQL 查询时

SELECT uid, rsvp_status FROM event_member WHERE uid = "{my uid written out}"
SELECT uid, rsvp_status FROM event_member WHERE uid IN ("{my uid written out}")

我得到以下空对象

{"data": []}

我想查询我朋友的公开活动。当我尝试使用以下任一查询执行此操作时

SELECT uid, rsvp_status FROM event_member WHERE uid = "{my friends uid written out}"
SELECT uid, rsvp_status FROM event_member WHERE uid IN ("{my friends uid written out}")

我再次得到以下空对象

{"data": []}

有什么建议么？