自定义 SQL 查询和 Spring Data JPA

Question

如何在 Spring Data JPA 中编写自定义查询？ 还有比下面更方便的方法吗？我以前是这样做的：public class TestCustomRepositoryImpl implements TestCustomRepository {    @PersistenceContext    private EntityManager entityManager;    @Override    public Double getValue(Long param) {        // Simple SQL query for example.        String queryString = "SELECT column_name1 FROM table_name1 "              + "WHERE column_name2 = " + param;        Query query = entityManager.createNativeQuery(queryString);        List resultList = query.getResultList();        if (!resultList.isEmpty()) {            Number value = (Number) resultList.get(0);            if (value != null) {                return value.doubleValue();            }        }        return 0.0;    }}然后我将自定义界面添加到我的 JPA 存储库中：public interface TestRepository extends JpaRepository<TestEntity, Long>, TestCustomRepository {}有没有更方便的方法？例如，我可以将 Spring Data 用于 CRUD 并使用 MyBatis 实现 TestCustomRepository 吗？你如何实现你的自定义方法？

Answer 1

You can write the native query in the repository like this:

1)

@Query("SELECT t.column_name1 FROM table_name1 t WHERE t.column_name2 =:param")

List<String> getValue(@Param("param") String param);

OR

2)@Query("SELECT t.column_name1 FROM table_name1 t WHERE t.column_name2 = 'param'", nativeQuery=true)

List<String> getValue();

Or you can use NamedQuery and add the query in the model only.

for eg: 

@Entity

@Table(name = "table_name1", schema="db_name")

@NamedQuery(name = "ENTITY.fetchParam",

        query = "SELECT t.column_name1 FROM table_name1 t WHERE t.column_name2 =:param "

)

public class Employee {

}

And have same method in the repository like:

@Repository

public interface TestRepository extends JpaRepository<Employee,Long>, TestRepositoryCustom {

    List<String> fetchParam(@Param("param") String param);

}