title: mysql pool.query doesn't work as expected
body: <p>I have a router that sends mysql result as response like:</p>
  
  <p><strong>router</strong></p>
  
  <pre><code>var pool = mysql.createPool({
      connectionLimit: account.MYSQL_CONNECTION_LIMIT,
      host: account.MYSQL_HOST,
      database: account.MYSQL_DATABASE,
      port: account.MYSQL_PORT,
      user: account.MYSQL_USER_ID,
      password: account.MYSQL_PASSWORD
  })
  
  router.get('/', async function (req, res) =&gt; {
      res.json({
              'activities': await pool.query(actQ(uid,gid))
       })
  })
  
  function actQ (uid, gid) {
      var query = "SELECT date_time, steps, calories, floors, distance, duration, pace FROM ACTIVITY ";
      query += " WHERE user_id = " + uid;
      query += "   AND game_id = " + mysql.escape(gid);
  
      return query
  }
  </code></pre>
  
  <p>It'd been working really well but It just started to work weird randomly. What I expect from <code>pool.query</code> is obviously a result from sql query but what I get is query information like this.</p>
  
  <p><strong>Response</strong></p>
  
  <pre><code>{
      "activities": {
          "domain": null,
          "_events": {},
          "_eventsCount": 0,
          "_callSite": {},
          "_ended": false,
          "_idleNext": null,
          "_idlePrev": null,
          "_idleStart": null,
          "_idleTimeout": -1,
          "_repeat": null,
          "sql": "SELECT date_time, steps, calories, floors, distance, duration, pace FROM ACTIVITY  WHERE user_id = 42741e32-b517-4655-92ca-af29815d236c   AND game_id = '498b36ff-0b90-11e8-97c8-061227ce9ef2'",
          "typeCast": true,
          "nestTables": false,
          "_resultSet": null,
          "_results": [],
          "_fields": [],
          "_index": 0,
          "_loadError": null
      }
  }
  </code></pre>
  
  <p>I increased connectionLimit more but It didn't solve this problem. It's been working really well and I double checked the MYSQL account but there was nothing wrong with them. Any ideas why this is happening?</p>