protected function createLikeExpression($operand1, $operand2)
    {
        /* @var $db \yii\db\Connection */
        $db = static::getDb();

        // In PGSQL we use case insensitive matching also.
        $like_function = $db->getDriverName() == 'pgsql' ? 'ILIKE' : 'LIKE';

        return [$like_function, $operand1, $operand2];
    }