我的文档中存储了一个数组:"properties":[{"createdate":1375981035,"updated":1375981035},{"accessdate":1375981035,"updated":1375981035},{"code":"4ffa04fe06000000","updated":1375981038}],执行更新以取消设置属性“代码”:db.coll.update({'properties.code':'4ffa04fe06000000'},{'$unset':{'properties.$':1}});我的结果是这样的:"properties":[{