exprIf example

's_articles_translations',
            self::TRANSLATION,
            $query->expr()->andX(
                $query->expr()->eq(self::TRANSLATION . '.articleID', self::PRODUCT . '.id'),
                $query->expr()->eq(self::TRANSLATION . '.languageID', $context->getShop()->getId()),
                $query->expr()->isNotNull(self::TRANSLATION_NAME),
                $query->expr()->neq(self::TRANSLATION_NAME, $query->expr()->literal(''))
            )
        );

        $query->addOrderBy(
            self::exprIf(
                $query->expr()->isNull(self::TRANSLATION_NAME),
                self::PRODUCT . '.name',
                self::TRANSLATION_NAME
            ),
            $sorting->getDirection()
        );
    }
}