小编Mar*_*ens的帖子

从我的MongoDB我想要等效的

  SELECT column1, column2
  FROM tbl

使用此代码,我可以获得所有"行"以及所有"列"

  DBCollection collection = database.getCollection("names");
  DBCursor cursor = collection.find();

例如,我想要所有 '行'但只有 '列':id,name,age

我该怎么做？

谢谢你的帮助!!

我有下面的代码有效:

if (aDBCursor.hasNext()) {
    DBObject aDbObject = aDBCursor.next();
    aDbObject.put("title", "Test Title");
    ArrayList<DBObject> department = new ArrayList<DBObject>();

    DBObject nested1 = new BasicDBObject();
    nested1.put("name", "Department A");
    nested1.put("id", 1);
    department.add(nested1);

    DBObject nested2 = new BasicDBObject();
    nested2.put("name", "Department B");
    nested2.put("id", 2);
    department.add(nested2);

    aDbObject.put("department", department);
    collection.save(aDbObject);
}

但是我在地图中有A部和B部的数据,如:

Map<Object,Object> map = new HashMap<Object,Object>();
map.put("1", "Department A");
map.put("2", "Department B");

保存这些数据的最佳/最简单方法是什么？有没有办法将地图直接放入mongo DB？或者我是否必须在地图上循环？

进入地图的数据已经从数据库中获取,如下所示:

String[] values = req.getParameterValues("departments");
Map<Object,Object> map = new HashMap<Object,Object>();

DBCollection collection = database.getCollection("Departments");
BasicDBObject query = new BasicDBObject();
query.put("id", new BasicDBObject("$in", values));
DBCursor …

我试图从这个JSON字符串中获取值,但我很难实现这一点.

{"DebugLogId":"1750550","RequestId":"17505503","Result":
{"Code":"","DebugLogId":"1750550","Message":""},
    "Suggestions":[
        {"Ranking":"1","Score":"60","Title":"This is a test message 1"},
        {"Ranking":"2","Score":"60","Title":"This is a test message 2"}         
    ]}

在"建议"中访问数据最简单的方法是什么？我正在使用GSON模块.理想情况下,我想把它全部放在HashMap中.

感谢您的帮助和/或建议!

谢谢你的帮助!

我有一个MongoDB,我希望获得两条记录或更多记录并将其放入地图中.如果我只有一个代码,则下面的代码可以正常query.put(ïd", "7");工作,但如果我在下面的代码中添加两个或更多代码,则代码不起作用.

    Map<Object,Object> map= new HashMap<Object,Object>();
    DBCollection collection = database.getCollection("Members");
    BasicDBObject query = new BasicDBObject();
    query.put("id", "7");
    query.put("id", "3");
    DBCursor cursor = collection.find(query);
    DBObject one;
    while(cursor.hasNext()) {
        one = cursor.next();
        map.put(one.get("id"),one.get("name"));
    }

如何在地图上获得两条或更多条记录？对于SQL,等价物将是SELCT * FROM Member WHERE id = 7 AND id = 3

更完美的是,如果我可以将列表作为查询,不确定这是否可行.