Spring Data JPA的低级错误

Posted 2020-12-27 zhu573514187

 1 //课程表
 2 @Entity
 3 public class Class {
 4     @GeneratedValue(strategy = GenerationType.AUTO)
 5     @Id
 6     private Long classID;// 课程编号             varchar(20) not null,
 7     private String className;// 课程名称          varchar(50),
 8     @Temporal(TemporalType.DATE)//(精确到年月日)
 9     private Date beginTime;//  开始时间         date,
10     @Temporal(TemporalType.DATE)//(精确到年月日)
11     private Date endTime;//结束时间             date,
12     private String classInfo;// 课程简介          text,
13     private double price;// 价格               numeric,
14     private int times;// 课时数               integer,
15     private int classMan;// 课程人数            int,
16 
17     @ManyToOne(cascade = CascadeType.ALL)
18     private Teacher teacher;//主教练         varchar(20),
19 
20 
21     @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY, mappedBy = "class_")
22     private List<Lesson> lessons;
23 //...省略getter和setter方法

 1 public interface ClassRepository extends JpaRepository<Class,Long> {
 2 
 3     @Query(value = "SELECT * FROM class WHERE classid=:ID",nativeQuery = true)
 4     Class findClassByID(@Param("ID")Long ID);
 5 
 6     @Modifying
 7     @Transactional
 8     @Query(value = "UPDATE class SET times=:times WHERE classid=:classid",nativeQuery = true)
 9     void updateClassTimes(@Param("times")int times,@Param("classid") Long classid);
10 
11 
12     @Query(value = "  select * FROM class where  DATE_FORMAT(begin_time,‘%Y%m%d‘) >=NOW()",nativeQuery = true)
13     List<Class> findClassByAfter();
14 
15     @Query(value = "  select * FROM class where  DATE_FORMAT(begin_time,‘%Y%m%d‘) <NOW()",nativeQuery = true)
16     List<Class> findClassByBefore();
17 
18     Page<Class> findByBeginTimeBefore(Date date,Pageable pageable);
19 
20 }

如果实体类里面属性名开头用大写字母，

在JPA中就不能通过查询的方法名和参数名来自动构造一个JPA OQL查询，

如18行的方法不能通过编译，

控制台会提示找不到该属性名，

千万告诫自己编码一定要规范。