Check if some query is undefined and define a callback in that case

I'm trying to do something like this:

var query = 'select max(count) from ' + series +
    ' where value = \'' + search + '\'';

if (db.query(query, callback) !== undefined) {

    return callback;
} else {

    return callback = [{
        name: series,
        columns: ['time', 'max'],
        points: [
            [0, 0]
        ]
    }];
}

I'm trying to verify if that query is undefined or the element searched doesn't exist in the influxdb, and then arm a callback just like if the element exist, the if sentence works, but the else return an empty array

The db parameter is where are the data base configurations.

EDIT:

Thanks Osukaa for your answe. I try what you sugest but don't have response. Here is the complete function with your changes:

var counter = function (config, callback) {

var count = 'select max(count) from ' + series + ' where value = \'' + search + '\'';

db.query(count, function (err, res) {
  if(err) return err;

  if(res.length == 0){
    return [{
      name: series,
      columns: ['time', 'max'],
      points: [
        [0, 0]
      ]
    }];
  }else{
    return res;
  }

});   
};

The console.log shows an empty array.

EDIT 2:

Thanks @Osukaa, unfortunately that don't work, this is the error that returns:

Debug: handler, error {"msec":395.7593630000483,"error":"Couldn't find series: items.type.updated"} Debug: internal, error Error: Couldn't find series: items.type.updated

Thanks.