Spring Data JPA的低级错误

程序员艳君技术 2022年11月6日

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

 public interface ClassRepository extends JpaRepository<Class,Long> {     @Query(value = "SELECT * FROM class WHERE classid=:ID",nativeQuery = true)
     Class findClassByID(@Param("ID")Long ID);     @Modifying
     @Transactional
     @Query(value = "UPDATE class SET times=:times WHERE classid=:classid",nativeQuery = true)
     void updateClassTimes(@Param("times")int times,@Param("classid") Long classid);     @Query(value = "  select * FROM class where  DATE_FORMAT(begin_time,'%Y%m%d') >=NOW()",nativeQuery = true)
     List<Class> findClassByAfter();     @Query(value = "  select * FROM class where  DATE_FORMAT(begin_time,'%Y%m%d') <NOW()",nativeQuery = true)
     List<Class> findClassByBefore();     Page<Class> findByBeginTimeBefore(Date date,Pageable pageable); }

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。