MongoDB的聚合查询

MongoDB的聚合查询 Java代码 www.2cto.com MongoClient mongoClient = null; try { mongoClient = new MongoClient(102.198.119.29, 27017); DB db = mongoClient.getDB(syslog); //设置Where条件 DBObject match = new BasicDBObject($match, new BasicDBOb

MongoDB的聚合查询

Java代码 www.2cto.com

MongoClient mongoClient = null;

try {

mongoClient = new MongoClient("102.198.119.29", 27017);

DB db = mongoClient.getDB("syslog");

//设置Where条件

DBObject match = new BasicDBObject("$match", new BasicDBObject(

"DATE",

(new BasicDBObject("$gt", "2012-11-28 00:19:00")).append(

"$lt", "2012-11-29 09:19:00")));

//设置分组字段

BasicDBObject groupFilters = new BasicDBObject("_id", "$PRIORITY");

//对分组字段统计行数

groupFilters.put("count", new BasicDBObject("$sum", 1));

BasicDBObject group = new BasicDBObject("$group", groupFilters);

//设置显示的字段集合

DBObject fields = new BasicDBObject("PRIORITY", 1);

fields.put("_id", "$PRIORITY");

DBObject project = new BasicDBObject("$project", fields);

AggregationOutput output = db.getCollection("messages").aggregate(

match, project, group);

System.out.println(output.getCommandResult());

} catch (UnknownHostException e) {

e.printStackTrace();

}

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