The following active record WHERE IN query does not work. According to the docs this should work:
$data = $dropDownData->find()
                    ->select('country, country_text')
                    ->distinct()
                    ->WHERE(['in', 'server', $servers]);
$listData = ArrayHelper::map($data,'country', 'country_text');
The sql equivalent is :
$query = "SELECT DISTINCT country, country_text 
          FROM `dropDownData` 
          WHERE server IN ({$servers})";
$servers just contains a string 1,2,4
What am I doing wrong here?