yii\db\mysql\QueryBuilder::addCommentOnColumn PHP Method

    public function addCommentOnColumn($table, $column, $comment)
    {
        $definition = $this->getColumnDefinition($table, $column);
        $definition = trim(preg_replace("/COMMENT '(.*?)'/i", '', $definition));
        return 'ALTER TABLE ' . $this->db->quoteTableName($table) . ' CHANGE ' . $this->db->quoteColumnName($column) . ' ' . $this->db->quoteColumnName($column) . (empty($definition) ? '' : ' ' . $definition) . ' COMMENT ' . $this->db->quoteValue($comment);
    }