Java 映射实体，作为映射值列出。执行DDL时出错"；如果存在“单行”，则删除表格；通过JDBC语句

我正在尝试创建一个应用程序，将Csv文件保存到数据库中。 在编译时，我有一个错误，数据没有完全保存在MySql数据库中

CVS文件的每一行都是一个列表，它是映射的一部分。 实体的映射注释有问题吗

以下是实体：

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<Long, LinesEntity> mapa;

public MapEntity() {
}

public Long getId() {
    return id;
}

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

public Map<Long, LinesEntity> getMapa() {
    return mapa;
}

public void setMapa(Map<Long, LinesEntity> mapa) {
    this.mapa = mapa;
}

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

---

好的，我把属性改为uptadte，它可以工作了。 spring.jpa.properties.hibernate.hbm2ddl.auto=update

但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

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

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