映射实体，列表为地图值。通过JDBC语句执行DDL“如果存在`single_line`，则丢弃表”时出错

问题描述

我正在尝试创建一个将Csv文件保存到数据库的应用程序。编译时出现错误，并且数据未完全保存在MySql DB中。

CVS文件的每一行都是一个列表，它是地图的一部分。我的实体的映射注释有问题吗？

这里是实体：

import javax.persistence.*;
import java.util.Map;

@Entity
@Table(name = "map_of_single_lists")
public class MapEntity {

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;

@ManyToMany(targetEntity=pl.manciak.excelparser.LinesEntity.class)
@MapKeyClass(Long.class)
private Map mapa;

public MapEntity() {
}

public Long getId() {
    return id;
}

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

public Map getMapa() {
    return mapa;
}

public void setMapa(Map mapa) {
    this.mapa = mapa;
}

和

@Entity
@Table(name="single_line")
public class LinesEntity implements Serializable{

@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;

@ElementCollection
private List singleLine;


public LinesEntity() {
}

public Long getId() {
    return id;
}

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

public List getSingleLine() {
    return singleLine;
}

public void setSingleLine(List singleLine) {
    this.singleLine = singleLine;
}

application.properties

spring.jpa.properties.hibernate.hbm2ddl.auto=create
logging.level.org.hibernate.SQL= DEBUG

spring.datasource.url=jdbc:mysql://127.0.0.1:3306/newapp
spring.datasource.username=root
spring.datasource.password=1234
spring.h2.console.enabled=true

错误：

2020-02-25 14:40:35.187 DEBUG 6504 --- [           main] org.hibernate.SQL                        : alter table `map_of_single_lists_mapa` drop foreign key `FKqcxcam32e9xly5k8nqppj7t9u`
2020-02-25 14:40:35.203  WARN 6504 --- [           main] o.h.t.s.i.ExceptionHandlerLoggedImpl     : GenerationTarget encountered exception accepting command : Error executing DDL "alter table `map_of_single_lists_mapa` drop foreign key `FKqcxcam32e9xly5k8nqppj7t9u`" via JDBC Statement

org.hibernate.tool.schema.spi.CommandAcceptanceException: Error executing DDL "alter table `map_of_single_lists_mapa` drop foreign key `FKqcxcam32e9xly5k8nqppj7t9u`" via JDBC Statement


....


2020-02-25 14:40:35.204 DEBUG 6504 --- [           main] org.hibernate.SQL                        : alter table `map_of_single_lists_mapa` drop foreign key `FKmy4dokdghspd6asaa66i2r8lu`
2020-02-25 14:40:35.206  WARN 6504 --- [           main] o.h.t.s.i.ExceptionHandlerLoggedImpl     : GenerationTarget encountered exception accepting command : Error executing DDL "alter table `map_of_single_lists_mapa` drop foreign key `FKmy4dokdghspd6asaa66i2r8lu`" via JDBC Statement

org.hibernate.tool.schema.spi.CommandAcceptanceException: Error executing DDL "alter table `map_of_single_lists_mapa` drop foreign key `FKmy4dokdghspd6asaa66i2r8lu`" via JDBC Statement


....


2020-02-25 14:40:35.245 DEBUG 6504 --- [           main] org.hibernate.SQL                        : drop table if exists `single_line`
2020-02-25 14:40:35.248  WARN 6504 --- [           main] o.h.t.s.i.ExceptionHandlerLoggedImpl     : GenerationTarget encountered exception accepting command : Error executing DDL "drop table if exists `single_line`" via JDBC Statement

org.hibernate.tool.schema.spi.CommandAcceptanceException: Error executing DDL "drop table if exists `single_line`" via JDBC Statement


....


2020-02-25 14:40:35.360 DEBUG 6504 --- [           main] org.hibernate.SQL                        : create table `single_line` (`id` bigint not null, primary key (`id`)) engine=InnoDB
2020-02-25 14:40:35.365  WARN 6504 --- [           main] o.h.t.s.i.ExceptionHandlerLoggedImpl     : GenerationTarget encountered exception accepting command : Error executing DDL "create table `single_line` (`id` bigint not null, primary key (`id`)) engine=InnoDB" via JDBC Statement

org.hibernate.tool.schema.spi.CommandAcceptanceException: Error executing DDL "create table `single_line` (`id` bigint not null, primary key (`id`)) engine=InnoDB" via JDBC Statement

思路：

好吧，我将属性更改为uptadte，并且可以正常工作。spring.jpa.properties.hibernate.hbm2ddl.auto =更新

但是我仍然不确定映射是否正确。在数据库中，我有23行，在csv文件中，我有100行