执行DDL alter table if exists任务时发生java错误。城市

Question

错误Error executing DDL "alter table if exists task.city add constraint FKtjrg7h2j3ehgycr3usqjgnc2u foreign key (id) references task.house" via JDBC Statement"我不知道如何解决它，我已经在寻找解决方案，但我检查了我的数据库和实体，一切都是正确的。我自己从头开始创建数据库。我在Postgresql工作。添加了错误日志

性质

spring.datasource.url=jdbc:postgresql://localhost:5432/innotechnum
spring.datasource.username=***
spring.datasource.password=***
spring.datasource.driver-class-name=org.postgresql.Driver
spring.jpa.database=postgresql
spring.jpa.hibernate.ddl-auto=update
spring.jpa.database-platform=org.hibernate.dialect.PostgreSQL10Dialect
spring.jpa.properties.hibernate.jdbc.lob.non_contextual_creation=true
spring.jpa.open-in-view= true
spring.jpa.show-sql=true

城市

@Data
@Entity
@Table(name = "city", schema = "task")
public class City {

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

    @Column(name = "id_region", nullable = false)
    private Integer id_region;
    @Column(name = "name", nullable = false)
    private String name;
}

房子

@Data
@Entity
@Table (name = "house", schema = "task")
public class House {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;
    
    @OneToMany(cascade = {CascadeType.DETACH, CascadeType.MERGE, CascadeType.PERSIST,
            CascadeType.REFRESH
    })
    @JoinColumn(name = "id")
    private Set<City> city;
    
    @OneToMany(mappedBy = "house")
    private Set<Contract> contract;

    @Column(name = "id_landlord", nullable = false)
    private Long id_landlord;
    @Column(name = "outside", nullable = false)
    private String outside;
    @Column(name = "rooms", nullable = false)
    private Integer rooms;
    @Column(name = "price", nullable = false)
    private Double price;
    @Column(name = "description", nullable = false)
    private String description;
}

日志：

org.hibernate.tool.schema.spi.CommandAcceptanceException: Error executing DDL "alter table if exists task.city add constraint FKtjrg7h2j3ehgycr3usqjgnc2u foreign key (id) references task.house" via JDBC Statement
    at org.hibernate.tool.schema.internal.exec.GenerationTargetToDatabase.accept(GenerationTargetToDatabase.java:67) ~[hibernate-core-5.4.20.Final.jar:5.4.20.Final]
    at org.hibernate.tool.schema.internal.AbstractSchemaMigrator.applySqlString(AbstractSchemaMigrator.java:559) ~[hibernate-core-5.4.20.Final.jar:5.4.20.Final]
    at
    ...

这是Postgresql给我的代码：

CREATE TABLE task.city
(
    id integer NOT NULL DEFAULT nextval('task.city_id_seq'::regclass),
    id_region integer NOT NULL,
    name character varying(250) COLLATE pg_catalog."default" NOT NULL,
    CONSTRAINT city_pkey PRIMARY KEY (id)
)

TABLESPACE pg_default;

ALTER TABLE task.city
    OWNER to root;

Answer 1

嗯，试试看

public class House {
  ...
  @ManyToOne(optional = false)
  @JoinColumn(name = "city_id", referencedColumnName = "id")
  private Set<City> city;
  ...
}

顺便说一句

• 不应在实体类中使用@Data lombok
• 春天。jpa。冬眠ddl auto=update可以将update更改为none。您应该自己管理模式

Answer 2

你不应该使用单向@OneToMany关联。尝试添加

@ManyToOne(fetchType = LAZY)
@JoinColumn(name = "house_id")
private House house;

去城市班

另外，你确定你需要一对多的联系吗？从一个家到另一个城市，而不是相反？城市可能有许多房屋，但房屋属于特定的城市