一对多：java.sql.SQLSyntaxErrorException：表'table_name'不存在

Question

我有 3 个表，“菜单”、“成分”和“菜单成分”（这个包含外键）检查图像 - Database

现在，当我在 Menu.java 类中设置一对多关系时，休眠以某种方式认为我有注释的 list 是表名：

成分.java：

@Entity
@Table(name = "ingredients")
public class Ingredients {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;

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

@Column(name = "description")
private String ingredientDescription;
//Getters/Setters/Constructor

菜单.java：

@Entity
@Table(name = "menu")
public class Menu {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private int id;

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

// Mapping To second table
@OneToMany(cascade = CascadeType.ALL)
private List<Ingredients> ingridients = new ArrayList<>();
// notice the name of this list 'ingridients' and then check the stacktrace.

主类：

@SpringBootApplication
public class RecipeappApplication implements CommandLineRunner {

@Autowired
RecipeRepository recipeRepository;

public static void main(String[] args) {
    SpringApplication.run(RecipeappApplication.class, args);

}

@Override
public void run(String... args) throws Exception {

    Menu menu = new Menu("Pizza");
    menu.getIngridients().add(new Ingredients("Cheese","3 slices"));
    menu.getIngridients().add(new Ingredients("Bacon","3 pieces"));


    recipeRepository.save(menu);
    //recipeRepository.save() <- is just the entitymanager.persist() call.
}

和错误：

java.lang.IllegalStateException: Failed to execute CommandLineRunner
...
Caused by: org.springframework.dao.InvalidDataAccessResourceUsageException: could not execute statement; SQL [n/a]; nested exception is org.hibernate.exception.SQLGrammarException: could not execute statement
...
Caused by: org.hibernate.exception.SQLGrammarException: could not execute statement
...
Caused by: java.sql.SQLSyntaxErrorException: Table 'recipe.menu_ingridients' doesn't exist

Answer 1

在您的数据库中，您有一个关联表 menu_ingredient，因此您需要使用 @JoinTable 对其进行映射：

@OneToMany(cascade = CascadeType.ALL)
@JoinTable(name = "menu_ingredient",
        joinColumns = @JoinColumn(name = "menu_id"),
        inverseJoinColumns = @JoinColumn(name = "ingredient_id"))
private List<Ingredients> ingredients;

• @JoinTable 注解用于使用第三张表连接两个表（此处为menu_ingredient）
• joinColumns：与当前实体（菜单）相关的第三个表的列。
• inverseJoinColumns：第三张表的列相关 关联实体（成分）。