CREATE TABLE advert ( id int(20) NOT NULL AUTO_INCREMENT COMMENT '主键', name varchar(100) COLLATE utf8mb4_bin NOT NULL COMMENT '广告名称', position_id int(20) NOT NULL COMMENT '广告位置ID', media_id int(20) NOT NULL COMMENT '广告图片ID', link varchar(500) COLLATE utf8mb4_bin NOT NULL COMMENT '广告链接', status int(1) unsigned zerofill NOT NULL COMMENT '状态,0：未启用，1：已启用，2：已结束', PRIMARY KEY (id) USING BTREE, KEY FK_ad_image (media_id), KEY FK_ad_position (position_id), CONSTRAINT FK_ad_image FOREIGN KEY (media_id) REFERENCES media_file (id) ON DELETE CASCADE ON UPDATE CASCADE, CONSTRAINT FK_ad_position FOREIGN KEY (position_id) REFERENCES ad_position (id) ON DELETE NO ACTION ON UPDATE NO ACTION ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin COMMENT='广告表'; CREATE TABLE ad_position ( id int(20) NOT NULL AUTO_INCREMENT COMMENT '主键', name varchar(50) COLLATE utf8mb4_bin NOT NULL COMMENT '位置名称', PRIMARY KEY (id) ) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin COMMENT='广告位置表'; CREATE TABLE media_file ( id int(20) NOT NULL AUTO_INCREMENT COMMENT '主键', name varchar(30) COLLATE utf8mb4_bin NOT NULL COMMENT '媒体文件名称', type tinyint(1) NOT NULL COMMENT '媒体文件类型：0-图片，1-视频', url varchar(500) COLLATE utf8mb4_bin NOT NULL COMMENT '媒体文件URL地址', PRIMARY KEY (id) ) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin COMMENT='广告媒体文件表'; springboot项目用java写出三张表的orm对象（使用jpa外键依赖）并且对advert表的添加和删除操作不会影响ad_position表的数据

以下是使用JPA外键依赖的三张表的ORM对象：

Advert表的ORM对象：

@Entity
@Table(name = "advert")
public class Advert {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @Column(name = "name")
    private String name;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "position_id")
    private AdPosition adPosition;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "media_id")
    private MediaFile mediaFile;

    @Column(name = "link")
    private String link;

    @Column(name = "status")
    private Integer status;

    // 构造函数、Getter、Setter方法省略
}

AdPosition表的ORM对象：

@Entity
@Table(name = "ad_position")
public class AdPosition {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @Column(name = "name")
    private String name;

    @OneToMany(mappedBy = "adPosition", cascade = CascadeType.ALL, orphanRemoval = true)
    private List<Advert> adverts = new ArrayList<>();

    // 构造函数、Getter、Setter方法省略
}

MediaFile表的ORM对象：

@Entity
@Table(name = "media_file")
public class MediaFile {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;

    @Column(name = "name")
    private String name;

    @Column(name = "type")
    private Integer type;

    @Column(name = "url")
    private String url;

    @OneToMany(mappedBy = "mediaFile", cascade = CascadeType.ALL, orphanRemoval = true)
    private List<Advert> adverts = new ArrayList<>();

    // 构造函数、Getter、Setter方法省略
}

在Advert表中，使用@ManyToOne注解创建与AdPosition表和MediaFile表之间的多对一关系，通过@JoinColumn注解指定外键的名称为position_id和media_id，并且设置fetch属性为LAZY，避免在查询Advert表时立即加载AdPosition表和MediaFile表的数据。

在AdPosition表和MediaFile表中，使用@OneToMany注解创建与Advert表之间的一对多关系，并且设置mappedBy属性为adPosition和mediaFile，表示Advert表中的adPosition和mediaFile属性维护了与AdPosition表和MediaFile表之间的关系。同时，设置cascade属性为CascadeType.ALL，表示级联保存、更新和删除操作，设置orphanRemoval属性为true，表示在Advert表中删除AdPosition表或MediaFile表的数据时，同时也会删除Advert表中对应的数据。

对于Advert表的添加和删除操作不影响AdPosition表和MediaFile表的数据，可以在AdPosition表和MediaFile表中设置@OneToMany注解的cascade属性为CascadeType.PERSIST和CascadeType.MERGE，表示只有在保存或更新Advert表时才会级联保存或更新AdPosition表和MediaFile表的数据，而在删除Advert表时不会级联删除AdPosition表和MediaFile表的数据。