有如下三个实体类:
User类:
@Entity
@Table(name = "user_")
public class User {
private int id;
private String username;
private Set<User> friends = new HashSet<User>();
@Id
@Column(name = "id_")
@GeneratedValue(strategy = GenerationType.IDENTITY)
public int getId() {
return id;
} public void setId(int id) {
this.id = id;
} @Column(name = "username_", length = 20)
public String getUsername() {
return username;
} public void setUsername(String username) {
this.username = username;
}
@ManyToMany
@JoinTable(name = "friend_",
joinColumns = { @JoinColumn(name = "userid_") },
inverseJoinColumns = { @JoinColumn(name = "friendid_") })
public Set<User> getFriends() {
return friends;
} public void setFriends(Set<User> friends) {
this.friends = friends;
}
}
Bulletin类:
@Entity
@Table(name = "bulletin_")
public class Bulletin {
private int id;
private String title;
private User user;
@Id
@Column(name = "id_")
@GeneratedValue
public int getId() {
return id;
} public void setId(int id) {
this.id = id;
} @Column(name = "title_", length = 30)
public String getTitle() {
return title;
} public void setTitle(String title) {
this.title = title;
}
@OneToMany
@Column(name = "userid_")
public User getUser() {
return user;
} public void setUser(User user) {
this.user = user;
}
}
这里有三张数据库表
1。user_表(id_,username_)2。bulletin_表(id_,title_,userid_)3。friend_表(id_,userid_,friendid_)
这里想在删user_表中的一条记录时,同时删除bulletin_(userid_="条件")和friend_表中的(userid_="条件"和friendid_="条件"),求高手帮忙,最好能在我代码的基础上改下,先谢了。在能解释下就更好了#11
User类:
@Entity
@Table(name = "user_")
public class User {
private int id;
private String username;
private Set<User> friends = new HashSet<User>();
@Id
@Column(name = "id_")
@GeneratedValue(strategy = GenerationType.IDENTITY)
public int getId() {
return id;
} public void setId(int id) {
this.id = id;
} @Column(name = "username_", length = 20)
public String getUsername() {
return username;
} public void setUsername(String username) {
this.username = username;
}
@ManyToMany
@JoinTable(name = "friend_",
joinColumns = { @JoinColumn(name = "userid_") },
inverseJoinColumns = { @JoinColumn(name = "friendid_") })
public Set<User> getFriends() {
return friends;
} public void setFriends(Set<User> friends) {
this.friends = friends;
}
}
Bulletin类:
@Entity
@Table(name = "bulletin_")
public class Bulletin {
private int id;
private String title;
private User user;
@Id
@Column(name = "id_")
@GeneratedValue
public int getId() {
return id;
} public void setId(int id) {
this.id = id;
} @Column(name = "title_", length = 30)
public String getTitle() {
return title;
} public void setTitle(String title) {
this.title = title;
}
@OneToMany
@Column(name = "userid_")
public User getUser() {
return user;
} public void setUser(User user) {
this.user = user;
}
}
这里有三张数据库表
1。user_表(id_,username_)2。bulletin_表(id_,title_,userid_)3。friend_表(id_,userid_,friendid_)
这里想在删user_表中的一条记录时,同时删除bulletin_(userid_="条件")和friend_表中的(userid_="条件"和friendid_="条件"),求高手帮忙,最好能在我代码的基础上改下,先谢了。在能解释下就更好了#11
解决方案 »
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