db.jason.find().sort({"rank":1})
{ "_id" : ObjectId("51ae517372779b7eeeb81342"), "name" : "jason" }
{ "_id" : ObjectId("51ae517372779b7eeeb81343"), "name" : "jason" }
{ "_id" : ObjectId("51ae513772779b7eeeb8133a"), "name" : "jason", "rank" : 0 }
{ "_id" : ObjectId("51ae513772779b7eeeb8133b"), "name" : "jason", "rank" : 1 }
{ "_id" : ObjectId("51ae513772779b7eeeb8133c"), "name" : "jason", "rank" : 2 }
我希望没有排名的文档能够结束排序而不是开始排序......但也要保持排名的项目按升序排列。这是可能的还是我应该使用字符串或高数字(如 99999)默认为空?