yii2 active record problem for DATE_FORMAT

I am using the following query in Active Record:

$consumption = PowerReading::find()

        ->select(['DATE_FORMAT( date_on,  "%m-%Y" ) AS MONTH', 'SUM( active_power )'])

        ->where(['receiving_station' => 'ARSS'])

        ->groupBy('DATE_FORMAT( date_on,  "%m-%Y" )')


The SQL getting generated is:

SELECT DATE_FORMAT( date_on,  "%m-%Y" ) AS MONTH, SUM( active_power ) FROM `power_reading` WHERE `receiving_station`='ARSS' GROUP BY DATE_FORMAT( date_on, `"%m-%Y" )`

As can be noticed, there is a bug in the generated GROUP BY statement. There is an extra ‘`’ in front of %m. Where have I gone wrong!?


Thanks, Master