关于JPA中使用原生SQL语句

最新推荐文章于 2024-07-31 00:13:48 发布

allen413

最新推荐文章于 2024-07-31 00:13:48 发布

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分类专栏： Java基础文章标签： SQL JPA C C++ C#

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本文介绍了一个使用Spring框架和JPA实现的Java类，该类提供了两个方法：一是通过课程ID查找教师姓名；二是通过课程ID查找学生列表。文章展示了如何利用EntityManager进行原生SQL查询，并通过事务管理确保数据的一致性和完整性。

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import org.springframework.context.ApplicationContext;
import org.springframework.orm.jpa.support.JpaDaoSupport;
import java.util.*;
import javax.persistence.*;

public class CustomerCourseDAO extends JpaDaoSupport implements ICustomerCourseDAO {

public String findTeacherNameByCourseId(Integer courseid) {
        String sql = "select concat(c.Given_Name,' ',c.Family_Name) as teachername from customer c,customer_course cc"
                + " where c.Customer_ID = cc.Customer_ID and cc.Related_Code = 2 and cc.Course_ID = " + courseid.intValue();
        try {
            EntityManagerFactory emf = getJpaTemplate().getEntityManagerFactory();
            EntityManager newEm = emf.createEntityManager();
            EntityTransaction newTx = newEm.getTransaction();
            newTx.begin();

            List result = newEm.createNativeQuery(sql).getResultList();
            String teachername = "";
            if(result.size()==1){
                teachername = (String)result.get(0);
            }
            newEm.getDelegate();
            newTx.commit();
            newEm.close();
            emf.close();

            return teachername;
        } catch (RuntimeException re) {
            logger.error("find Teacher's Name by courseId failed", re);

            throw re;
        }
    }

    //add by edwin， 2007-11-08 测试通过
    @SuppressWarnings(value = "unchecked")
    public List<CustomerCourse> findTeaStuByCourseId(Integer id) {
        String sql = "select model.* from customer_course model " + "where model.Related_Code = 1 and model.Course_ID = " + id.intValue();

        try {
            EntityManagerFactory emf = getJpaTemplate().getEntityManagerFactory();
            EntityManager newEm = emf.createEntityManager();
            EntityTransaction newTx = newEm.getTransaction();
            newTx.begin();

            @SuppressWarnings(value = "unchecked")
            List<CustomerCourse> stu = newEm.createNativeQuery(sql,CustomerCourse.class).getResultList();
            newTx.commit();
            newEm.close();
            emf.close();

            return stu;
        } catch (RuntimeException re) {
            logger.error("find Teacher's students by courseId failed", re);

            throw re;
        }
    }

}