MongoDB 查询总结

1、含日期查询 从起始时间到结束时间BasicDBObject queryObj = new BasicDBObject();queryObj.put("date",new BasicDBObject().append("$gte",starttime).append("$lt",endtime));2、distinct 查询BasicDBObject queryObj = new BasicDBObject();coll.distinct("field_name",queryObj);// field_name 为数据库中需要distinct的字段名称，queryObj为查询条件 ，先执行查询条件后在distinct；返回为一个list集合 里面存放所有不重复的 field_name.这种方式还是有中缺陷，如果数据量过大 list可能超出容量，不好控制，可以使用group by的方法替换3、exists 查询BasicDBObject basicObj = new BasicDBObject();BasicDBObject andSearch = new BasicDBObject();andSearch.put("$gte", start.getTime());andSearch.put("$lt", end.getTime());basicObj.put("date", andSearch);basicObj.put("field_name", new BasicDBObject("$exists", true)); //若数据库中 field_name 这个字段有值 (包含null)，则符合条件，反之这条记录没有这个字段则不符合条件4、group 查询 （分组查询）Map<String, Integer> map = new HashMap<String,Integer>();DBCollection coll = MongoDB.getDBCollection("user_processed_corpus");DBObject fields = new BasicDBObject();fields.put("cust_name", "$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("$match",matchObj);AggregationOutput output = coll.aggregate(match, group);Iterable<DBObject> results = output.results();Iterator<DBObject> it = results.iterator();while(it.hasNext()){DBObject obj = it.next();DBObject name = (DBObject) obj.get("_id");Object cust_name =name.get("cust_name");if(CommonUtil.isNotNull(cust_name)){map.put(cust_name.toString(), Integer.valueOf(obj.get("count").toString()));}} 4.2 group（方式2）　　public static void group(){ BasicDBObject group = new BasicDBObject(); group.put("_id", "$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")); } 5、addToSet(只能确保添加到记录，不能影响原有记录数据) 相同的数据则不添加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()); } 6、or 查询 将多个查询条件加入一个list中 用$or 连接list中的查询条件即可public static void test1(){ BasicDBObject query1 = new BasicDBObject(); BasicDBObject query2 = new BasicDBObject(); query1.put("count", new BasicDBObject("$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); } 7、in 查询 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("$in", cond)); 8 DBCursor cur = coll.find(query); 9 while(cur.hasNext()){ 10 System.out.println(cur.next()); 11 } 12 } 8、addToSet的另外一种用法（本质相同） 对分组之后的数据在进行操作userid question1　　　　a1　　　　b2　　　　c　　2　　　　a　　　2　　　　b1　　　　a　　3　　　　c　　3　　　　b　　3　　　　a 1 public static void group1(){ 2 BasicDBObject obj = new BasicDBObject(); 3 BasicDBObject query = new BasicDBObject(); 4 BasicDBObject match = new BasicDBObject(); 5 BasicDBObject group = new BasicDBObject(); 6 BasicDBObject g1 = new BasicDBObject(); 7 //第一个分组 （userid 和 question 共同作为分组字段） 8 g1.put("userid", "$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("$group", groupFields1);25 26 AggregationOutput out = coll.aggregate(match,obj,group1);27 CommandResult result = out.getCommandResult();28 BasicDBList record = (BasicDBList) result.get("result");29 System.out.println(record.size());30 }注1：第一次分组的结果[{"_id" : {"userid" : "0003","question" : "how"},"count" : 30,"userid" : ["0003"],"question" : ["how"]}, {"_id" : {"userid" : "0002","question" : "I am comming"},"count" : 1,"userid" : ["0002"],"question" : ["I am comming"]}, {"_id" : {"userid" : "0002","question" : "2323"},"count" : 1,"userid" : ["0002"],"question" : ["2323"]}, {"_id" : {"userid" : "0002","question" : "how"},"count" : 38,"userid" : ["0002"],"question" : ["how"]}, {"_id" : {"userid" : "0001","question" : "I comming"},"count" : 1,"userid" : ["0001"],"question" : ["I comming"]}, {"_id" : {"userid" : "0002","question" : "123"},"count" : 1,"userid" : ["0002"],"question" : ["123"]}, {"_id" : {"userid" : "0001","question" : "I am "},"count" : 1,"userid" : ["0001"],"question" : ["I am "]}, {"_id" : {"userid" : "0001","question" : "I am comming"},"count" : 4,"userid" : ["0001"],"question" : ["I am comming"]}]结果解释：_id 中的内容为分组的字段是唯一的，故作为_id 后面的count userid 和question都是在分组过程中手动添加上去的，这个其实就当做中间表 以便下面的数据统计和操作9、模糊查询（pattern）String like = "...";Pattern pattern = Pattern.compile("^.*"+like+".*$", Pattern.CASE_INSENSITIVE);BasicDBObject obj = new BasicDBObject();obj.put("name",pattern);coll.find(obj);10、$eleMatch 查询（数组匹配查询）DBObject edit = new BasicDBObject();edit.put("slotname", "content");query.put("slotbind", new BasicDBObject("$elemMatch", edit)); 不难发现主要用到BasicDBObject、BasicDBList、DBCursor这三个类。BasicDBObject好比一个map，好比使用json查询中的{} 。BasicDBList是个list，用于or，nin等条件查询。DBCursor用于遍历结果集。其实只要将对应的json查询使用这3个类转化一下，就能写出对应的java代码了。