Question

我正在分析Spring Data为我的模型生成的查询：

public class Description {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Short id;

    @Version
    Timestamp version;

    @OneToOne(mappedBy="description") 
    @Getter @Setter
    Customer customer;

    @Getter @Setter
    String description;
}

public class WorkPlace {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Short id;

    @Version
    Timestamp version;

    @Getter @Setter
    String workplaceName;

    @OneToMany(mappedBy="workPlace")
    Set<Customer> customers;

}

可能不重要的部分：

public class Address {

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

    @Version
    Timestamp version;

    @ManyToMany @Getter
    List<Customer> customers = new LinkedList<>();

    @Getter @Setter
    String street;
}

public class CustomerOrder {

    @Id
    @GeneratedValue
    private Short id;

    @Version
    Timestamp version;

    @ManyToOne @Getter @Setter
    Customer customer;

    @Getter @Setter
    int quantity;
}

我有一个适用于客户的Spring Data CRUD存储库。调用后：repo.findOne（（简称）1）生成以下查询：

select customer0_.id as id11_2_, customer0_.description_id as descript4_11_2_, customer0_.name as name11_2_, customer0_.version as version11_2_, customer0_.workPlace_id as workPlace5_11_2_, descriptio1_.id as id12_0_, descriptio1_.description as descript2_12_0_, descriptio1_.version as version12_0_, workplace2_.id as id15_1_, workplace2_.version as version15_1_, workplace2_.workplaceName as workplac3_15_1_ 
from Customer customer0_ left outer join 
     Description descriptio1_ on customer0_.description_id=descriptio1_.id left outer join 
     WorkPlace workplace2_ on customer0_.workPlace_id=workplace2_.id 
where customer0_.id=?

select customer0_.id as id11_2_, customer0_.description_id as descript4_11_2_, customer0_.name as name11_2_, customer0_.version as version11_2_, customer0_.workPlace_id as workPlace5_11_2_, descriptio1_.id as id12_0_, descriptio1_.description as descript2_12_0_, descriptio1_.version as version12_0_, workplace2_.id as id15_1_, workplace2_.version as version15_1_, workplace2_.workplaceName as workplac3_15_1_ 
from Customer customer0_ left outer join 
     Description descriptio1_ on customer0_.description_id=descriptio1_.id left outer join 
     WorkPlace workplace2_ on customer0_.workPlace_id=workplace2_.id 
where customer0_.description_id=?

为什么我们需要第二个查询？第一个还不够吗？我错过了什么，或者同一个查询（相同的结果）被调用了两次？

Spring Data生成的查询 - OneToOne映射

0 个答案: