jpqa_boolean.java

// reference: https://codingexplained.com/coding/java/spring-framework/return-boolean-value-from-spring-data-jpa-query

@Repository
public interface CompanyRepository extends JpaRepository<Company, Integer> {
    @Query("SELECT CASE WHEN COUNT(c) > 0 THEN true ELSE false END FROM Company c WHERE c.name = :companyName")
    boolean existsByName(@Param("companyName") String companyName);
}