MongoDB里面怎么 查最值

怎么在MongoDB里面怎么 查最值  就好像SQL语句的select MAX(row) form ....

我现在知道了，现在拿出来和大家分享一下吧  

DBObject ref = new BasicDBObject();

ref.put("auth_id", authId);

ref.put("weibo_type", weiboType);

DBObject keys = new BasicDBObject("weibo_id", 1);

DBObject orderBy = new BasicDBObject("weibo_id", -1);// -1标示降序 1表示升序

DBCursor dbc = statusColl.find(ref, keys).sort(orderBy).limit(1);

DBObject dbo = null;

try {

dbo = dbc.next();

} catch (NoSuchElementException e) {

return -1L;

}

return (Long) dbo.get("weibo_id");

大概就是上面那个样子啦，根据您自己的业务需求，写出符合条件的代码吧，主要就是find()和limit()这两根函数而已，下面的这个大家可以无视，我是写给自己看的

List<Status> list = new LinkedList<Status>();

DBObject ref = new BasicDBObject();

ref.put("user_id", userId);

DBObject orderBy = new BasicDBObject("create_at", -1); // -1标示降序 1表示升序

DBCursor res = homePagesColl.find(ref).sort(orderBy).skip(

(pageNumber - 1) * nPerPage).limit(nPerPage);

while (res.hasNext()) {

Object obj = res.next().get("weibo_content");

Status sta = new Status(new JSONObject(obj.toString()));

list.add(sta);

}

return list;