var result = db.getCollection('table').find({})
//边读边取插入
while(result.hasNext()){
var next = result.next();
//获取的长度,ObjectId("5d2435478960f9c14292f2a7")
//从索引10开始截取
var length = next._id.toString().length-10-2
var _str = next._id.toString().substr(10,length);
printjson(_str);
printjson(next._id);
}