<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

@Data
public class Account {
    int id;
    String username;
    String password;
}

@Data
@Entity   //表示這個類是一個實體類
@Table(name = "account")    //對應的數(shù)據庫中表名稱
public class Account {
    @GeneratedValue(strategy = GenerationType.IDENTITY)   //生成策略，這里配置為自增
    @Column(name = "id")    //對應表中id這一列
    @Id     //此屬性為主鍵
    int id;
    @Column(name = "username")   //對應表中username這一列
    String username;
    @Column(name = "password")   //對應表中password這一列
    String password;
}

spring:
  jpa:
    #開啟SQL語句執(zhí)行日志信息
    show-sql: true
    hibernate:
      #配置為檢查數(shù)據庫表結構，沒有時會自動創(chuàng)建
      ddl-auto: update

@Repository
public interface AccountRepository extends JpaRepository<Account, Integer> {
}

@Resource
AccountRepository repository;
@Test
void contextLoads() {
    Account account = new Account();
    account.setUsername("小紅");
    account.setPassword("1234567");
    System.out.println(repository.save(account).getId());   //使用save來快速插入數(shù)據，并且會返回插入的對象，如果存在自增ID，對象的自增id屬性會自動被賦值，這就很方便了
}

@Test
void contextLoads() {
  	//默認通過通過ID查找的方法，并且返回的結果是Optional包裝的對象，非常人性化
    repository.findById(1).ifPresent(System.out::println);
}

@Repository
public interface AccountRepository extends JpaRepository<Account, Integer> {
    //按照表中的規(guī)則進行名稱拼接，不用刻意去記，IDEA會有提示
    List<Account> findAllByUsernameLike(String str);
}

@Test
void contextLoads() {
    repository.findAllByUsernameLike("%明%").forEach(System.out::println);
}

@Repository
public interface AccountRepository extends JpaRepository<Account, Integer> {
    List<Account> findAllByUsernameLike(String str);
    Account findByIdAndUsername(int id, String username);
    //也可以使用Optional類進行包裝，Optional<Account> findByIdAndUsername(int id, String username);
}

@Test
void contextLoads() {
    System.out.println(repository.findByIdAndUsername(1, "小明"));
}

@Repository
public interface AccountRepository extends JpaRepository<Account, Integer> {
    List<Account> findAllByUsernameLike(String str);
    Account findByIdAndUsername(int id, String username);
    //使用exists判斷是否存在
    boolean existsAccountById(int id);
}

@Data
@Entity
@Table(name = "users_detail")
public class AccountDetail {
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Id
    int id;
    @Column(name = "address")
    String address;
    @Column(name = "email")
    String email;
    @Column(name = "phone")
    String phone;
    @Column(name = "real_name")
    String realName;
}

@Data
@Entity
@Table(name = "users")
public class Account {
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    @Id
    int id;
    @Column(name = "username")
    String username;
    @Column(name = "password")
    String password;
    @JoinColumn(name = "detail_id")   //指定存儲外鍵的字段名稱
    @OneToOne    //聲明為一對一關系
    AccountDetail detail;
}

@Test
void pageAccount() {
    repository.findById(1).ifPresent(System.out::println);
}

@JoinColumn(name = "detail_id")
@OneToOne(fetch = FetchType.LAZY)    //將獲取類型改為LAZY
AccountDetail detail;

@Transactional   //懶加載屬性需要在事務環(huán)境下獲取，因為repository方法調用完后Session會立即關閉
@Test
void pageAccount() {
    repository.findById(1).ifPresent(account -> {
        System.out.println(account.getUsername());   //獲取用戶名
        System.out.println(account.getDetail());  //獲取詳細信息（懶加載）
    });
}

@JoinColumn(name = "detail_id")
@OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL) //設置關聯(lián)操作為ALL
AccountDetail detail;

@Test
void addAccount(){
    Account account = new Account();
    account.setUsername("Nike");
    account.setPassword("123456");
    AccountDetail detail = new AccountDetail();
    detail.setAddress("重慶市渝中區(qū)解放碑");
    detail.setPhone("1234567890");
    detail.setEmail("73281937@qq.com");
    detail.setRealName("張三");
  	account.setDetail(detail);
    account = repository.save(account);
    System.out.println("插入時，自動生成的主鍵ID為："+account.getId()+"，外鍵ID為："+account.getDetail().getId());
}

@JoinColumn(name = "uid")  //注意這里的name指的是Score表中的uid字段對應的就是當前的主鍵，會將uid外鍵設置為當前的主鍵
@OneToMany(fetch = FetchType.LAZY, cascade = CascadeType.REMOVE)   //在移除Account時，一并移除所有的成績信息，依然使用懶加載
List<Score> scoreList;

@Data
@Entity
@Table(name = "users_score")   //成績表，注意只存成績，不存學科信息，學科信息id做外鍵
public class Score {
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    @Id
    int id;
    @OneToOne   //一對一對應到學科上
    @JoinColumn(name = "cid")
    Subject subject;
    @Column(name = "socre")
    double score;
    @Column(name = "uid")
    int uid;
}

@Data
@Entity
@Table(name = "subjects")   //學科信息表
public class Subject {
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "cid")
    @Id
    int cid;
    @Column(name = "name")
    String name;
    @Column(name = "teacher")
    String teacher;
    @Column(name = "time")
    int time;
}

@Transactional
@Test
void test() {
    repository.findById(1).ifPresent(account -> {
        account.getScoreList().forEach(System.out::println);
    });
}

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "tid")   //存儲教師ID的字段，和一對一是一樣的，也會當前表中創(chuàng)個外鍵
Teacher teacher;

@Data
@Entity
@Table(name = "teachers")
public class Teacher {
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Id
    int id;
    @Column(name = "name")
    String name;
    @Column(name = "sex")
    String sex;
}

@Transactional
@Test
void test() {
    repository.findById(3).ifPresent(account -> {
        account.getScoreList().forEach(score -> {
            System.out.println("課程名稱："+score.getSubject().getName());
            System.out.println("得分："+score.getScore());
            System.out.println("任課教師："+score.getSubject().getTeacher().getName());
        });
    });
}

@ManyToMany(fetch = FetchType.LAZY)   //多對多場景
@JoinTable(name = "teach_relation",     //多對多中間關聯(lián)表
        joinColumns = @JoinColumn(name = "cid"),    //當前實體主鍵在關聯(lián)表中的字段名稱
        inverseJoinColumns = @JoinColumn(name = "tid")   //教師實體主鍵在關聯(lián)表中的字段名稱
)
List<Teacher> teacher;

@Repository
public interface AccountRepository extends JpaRepository<Account, Integer> {
    @Transactional    //DML操作需要事務環(huán)境，可以不在這里聲明，但是調用時一定要處于事務環(huán)境下
    @Modifying     //表示這是一個DML操作
    @Query("update Account set password = ?2 where id = ?1") //這里操作的是一個實體類對應的表，參數(shù)使用?代表，后面接第n個參數(shù)
    int updatePasswordById(int id, String newPassword);
}

@Test
void updateAccount(){
    repository.updatePasswordById(1, "654321");
}

@Transactional
@Modifying
@Query(value = "update users set password = :pwd where username = :name", nativeQuery = true) //使用原生SQL，和Mybatis一樣，這里使用 :名稱 表示參數(shù)，當然也可以繼續(xù)用上面那種方式。
int updatePasswordByUsername(@Param("name") String username,   //我們可以使用@Param指定名稱
                             @Param("pwd") String newPassword);

@Test
void updateAccount(){
    repository.updatePasswordByUsername("Admin", "654321");
}