mongodb_修改器($inc/$set/$unset/$push/$pop/upsert......)
db.b.insert({"uid":"201203","type":"1",size:10})>db.b.find(){"_id":ObjectId("5003b6135af21ff428dafbe6"),"uid":"201203","type":"1","size":10}>db.b.update({"uid":"201203"},{"$inc":{"size":1}})>db.b.find