MongoDB 查询总结

Map<String, Integer> map = new HashMap<String,Integer>();
DBCollection coll = MongoDB.getDBCollection("user_processed_corpus");
DBObject fields = new BasicDBObject();
fields.put("cust_name", "$cust_name");
DBObject groupField = new BasicDBObject();
groupField.put("_id", fields);
groupField.put("count", new BasicDBObject("$sum",1));
DBObject group = new BasicDBObject("$group",groupField);
BasicDBObject matchObj = new BasicDBObject();
matchObj.put("date",new BasicDBObject("$lt", end.getTime()).append("$gt",start.getTime()));
matchObj.put("userid", userid);
matchObj.put("from", from);
DBObject match = new BasicDBObject("$match",matchObj);
AggregationOutput output = coll.aggregate(match, group);
Iterable<DBObject> results = output.results();
Iterator<DBObject> it = results.iterator();
while(it.hasNext()){
DBObject obj = it.next();
DBObject name = (DBObject) obj.get("_id");
Object cust_name =name.get("cust_name");
if(CommonUtil.isNotNull(cust_name)){
map.put(cust_name.toString(), Integer.valueOf(obj.get("count").toString()));
}
}

　　public static void group(){
        BasicDBObject group = new BasicDBObject();
        group.put("_id", "$userid");
        group.put("count", new BasicDBObject("$sum",1));
        AggregationOutput output = coll.aggregate(new BasicDBObject("$group",group));
        DBObject obj = output.getCommand();
        System.out.println(obj);
        CommandResult result = output.getCommandResult();
        System.out.println(result.get("result"));
    }

public static void addToSetAndEachElementInArray(String _id){  
            List list = new ArrayList();  
            list.add("str0");  
            list.add("str1");  
            list.add(new BasicDBObject("arr90",90));
            BasicDBObject idObj = new BasicDBObject("_id", new ObjectId(_id));
            BasicDBObject updateObj = new BasicDBObject();
            updateObj.put("$addToSet", new BasicDBObject("arrays",new BasicDBObject("$each",list)));
            WriteResult result = coll.update(idObj,updateObj);
            System.out.println("update count:"+result.getN());  
 } 

public static void test1(){
        BasicDBObject query1 = new BasicDBObject();
        BasicDBObject query2 = new BasicDBObject();
        query1.put("count", new BasicDBObject("$exists",false));
        query2.put("count", new BasicDBObject("$exists",true));
        BasicDBList list = new BasicDBList();
        list.add(query2);
        list.add(query1);
        BasicDBObject query = new BasicDBObject();
        query.put("$or", list);
        int count = coll.find(query).count();
        System.out.println(count);
        
    }

 1  public void findByINQuery(int value1,int value2){  
 2         coll = getCollection("ParentColl");  
 3         BasicDBObject query=new BasicDBObject();  
 4         BasicDBList cond=new BasicDBList();  
 5         cond.add(value1);  
 6         cond.add(value2);  
 7         query.put("intData",new BasicDBObject("$in", cond));  
 8         DBCursor cur = coll.find(query);  
 9         while(cur.hasNext()){  
10             System.out.println(cur.next());  
11         }  
12     }  

 1 public static void group1(){
 2             BasicDBObject obj = new BasicDBObject();
 3             BasicDBObject query = new BasicDBObject();
 4             BasicDBObject match = new BasicDBObject();
 5             BasicDBObject group = new BasicDBObject();
 6             BasicDBObject g1 = new BasicDBObject();
 7             //第一个分组 （userid 和 question 共同作为分组字段）
 8             g1.put("userid", "$userid");
 9             g1.put("question", "$question");
10             group.put("_id", g1);
11             //可以额外的添加一些字段（以便下次的统计操作）
12             group.put("count", new BasicDBObject("$sum",1));
13             group.put("userid",new BasicDBObject("$addToSet", "$userid")); 
14             group.put("question",new BasicDBObject("$addToSet", "$question")); 
15             obj.put("$group", group);
16             match.put("$match", query);
17             
18             //对第一次分组产生的结果进行再次分组（第一次分组的结果见注1）
19             DBObject _group = new BasicDBObject();
20             _group.put("question", "$question");
21             DBObject groupFields1 = new BasicDBObject("_id", _group);
22             groupFields1.put("user_sum", new BasicDBObject("$sum", 1));
23             BasicDBObject group1 = new BasicDBObject();
24             group1.append("$group", groupFields1);
25             
26             AggregationOutput out =  coll.aggregate(match,obj,group1);
27             CommandResult result =  out.getCommandResult();
28             BasicDBList record = (BasicDBList) result.get("result");
29             System.out.println(record.size());
30     }