org.springframework.boot
            spring-boot-starter-data-jdbc
        org.springframework.boot
            spring-boot-starter-web
        mysql
            mysql-connector-java
        org.springframework.boot
            spring-boot-devtools
            runtimetrueorg.springframework.boot
            spring-boot-starter-test
            testorg.junit.vintage
                    junit-vintage-engine
                org.springframework.boot
            spring-boot-starter-data-jpa
        

spring.datasource.url=jdbc:mysql://localhost:3306/v_chat?useSSL=false&useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.username=root
spring.datasource.password=123456


# JPA配置
spring.jpa.database=mysql
# 在控制台打印SQL
spring.jpa.show-sql=true
# 数据库平台
spring.jpa.database-platform=mysql
# 每次启动项目时，数据库初始化策略
spring.jpa.hibernate.ddl-auto=update
# 指定默认的存储引擎为InnoDB
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL57Dialect
#遇到大写字母 加”_”的命名, 驼峰命名
spring.jpa.hibernate.naming.physical-strategy=org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy

ddl-auto:create----每次运行该程序，没有表格会新建表格，表内有数据会清空

ddl-auto:create-drop----每次程序结束的时候会清空表

ddl-auto:update----每次运行程序，没有表格会新建表格，表内有数据不会清空，只会更新

ddl-auto:validate----运行程序会校验数据与数据库的字段类型是否相同，不同会报错

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

/**
 * 
 * User -> 用户实体类
 * 
 *
 * @author 撸小鱼
 * Copyright (c) lofish@foxmail.com
 */
@Entity(name = "t_user")
public class User{

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String username;
    private String address;

    public Long getId(){
        return id;
    }

    public void setId( Long id ){
        this.id = id;
    }

    public String getUsername(){
        return username;
    }

    public void setUsername( String username ){
        this.username = username;
    }

    public String getAddress(){
        return address;
    }

    public void setAddress( String address ){
        this.address = address;
    }
}

import net.lofish.xpra.model.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;

import java.util.List;

/**
 * 
 * UserDao -> dao层
 * 
 *
 * @author 撸小鱼
 * Copyright (c) lofish@foxmail.com
 */
public interface UserDao extends JpaRepository{

    List getUserByAddressEqualsAndIdLessThanEqual( String address, Long id );
    
    //SQL nativeQuery的值是true 执行的时候不用再转化
    @Query( value = "select * from t_user where id=(select max(id) from t_user)", nativeQuery = true )
    User maxIdUser();

}

@SpringBootTest
class SpringbootXpraApplicationTests{


    @Autowired
    UserDao userDao;


    @Test
    void contextLoads(){
    }


    @Test
    void testUserDao(){
        userDao.getUserByAddressEqualsAndIdLessThanEqual( "abc", 1l );
    }

}

Hibernate: select user0_.id as id1_0_, user0_.address as address2_0_, user0_.username as username3_0_ from t_user user0_ where user0_.address=? and user0_.id