db.help();
db.stats();
show dbs;
use videodb;
db.dropDatabase();
db.createCollection("videos");
show collections;
db.videos.drop();
db.videos.renameCollection("movies");
db.videos.find();
db.videos.inseart({"title":"Bike","tag":"{'cool','mountain'}"});
db.videos.update({"_id":ObjectId("51a8bdf44b75ea7cfd331e7f")},{$set:{'sort':'new'}});
db.videos.update({"_id":ObjectId("51966fc9e66501b29f13b47e")},{$set:{tag:['scubadiving','skydiving']}});
db.videos.update({"title":"Skydiving"},{$set:{"bad":"5","view":"1000"}});
db.videos.update({"like":"500"},{$rename:{"cate":"category"}},false,true);
db.videos.update({"like":"500"},{$rename:{"like":"good"}},false,true);
db.videos.update({"title":"Skydiving"},{$set:{"timestamp":(new Date()).getTime()}});
db.videos.remove({"userId":"test"});
db.videos.find({$and: [{"videoId": "427e096b2af75b5d45000002"},{"userId": "527e096b2af75b5d45000002"}]});