title: How to select from multiple databases in Android Room(How to attach databases)
body: <p>As you know we can select from multiple databases using attach command like this:</p>
  
  <pre><code>String path = DBHelper.getDatabasePath(context);
  String sql = "ATTACH DATABASE '" + path + "/" + dbname.toString()
                  + ".db' AS \"" + dbname.toString() + "\";";
  db.execSQL(sql);
  </code></pre>
  
  <p>Then by using Cursor, we can do select from them. </p>
  
  <p>By using Android Room, How can I do this? Is there any attachment or similar command to do this?</p>