title: How to group data by column value?
body: <p>I have some data like this:</p>
  
  <pre><code>[ 
   { date: '02.09.2013',
      start_at: '22:00',
      team1: 'Арсенал Саранди',
      team2: 'Архентинос Жуниорс',
      score1: '-',
      score2: '-',
      chemp: 'Аргентина. Инисиаль',
      _id: 52246c1f5fb4360000000001 },
    { date: '02.09.2013',
      start_at: '00:30',
      team1: 'Крузейро',
      team2: 'Васку да Гама',
      score1: '5',
      score2: '3',
      chemp: 'Бразилия. Серия А',
      _id: 52246c1f5fb4360000000002 },
    { date: '02.09.2013',
      start_at: '03:15',
      team1: 'Сан-Лоренсо',
      team2: 'Ривер Плейт',
      score1: '1',
      score2: '0',
      chemp: 'Аргентина. Инисиаль',
      _id: 52246c1f5fb4360000000003 },
    { date: '02.09.2013',
      start_at: '22:00',
      team1: 'Эшторил',
      team2: 'Академика',
      score1: '-',
      score2: '-',
      chemp: 'Португалия. Лига Сагреш',
      _id: 52246c205fb4360000000004 } 
   ]
  </code></pre>
  
  <p>How I can get it and group it by chemp value?</p>
  
  <p><strong>Update:</strong>
  Final solutions is:</p>
  
  <pre><code>collection.aggregate({ $project : {
                   chemp: 1,
                   team1: 1,
                   team2: 1,
                   score1: 1,
                   score2: 2,
                   start_at: 1
                 }
      }, { $group : { _id : { chemp : "$chemp" }, games: {$push: {team1: "$team1", team2: "$team2", score1: "$score1", score2: "$score2", start_at: "$start_at"}} } }, function(err, data){
          db.close();
        }
      )
  </code></pre>