Java 正在尝试运行命名查询

我正在做以下工作：

@Entity
@SqlResultSetMapping(name="getxxxx",
        entities=@EntityResult(xxxx.class,
            fields = {
                    @FieldResult(name="x1", column = "x1"),
                    @FieldResult(name="x2", column = "x2")}))

@NamedNativeQuery(name=" getxxxx ",
    query="select x1, x2 from yyyy", 
    resultSetMapping=" getxxxx ")

} )public class xxxx{

    .
    .
    .
    public xxxx() {

}

我得到一个错误： 无法解析表xxxx，类xxxx不是映射到我的源中的表， 我试图查询数据库并将结果返回到我的类中

---

有可能吗？

在这种情况下，我要做的第一件事就是删除@Entity注释。然后更改类名或本机查询名，其中一个是xxxx，另一个是zzzz，这样我就知道运行时在抱怨什么了。

在这种情况下，我要做的第一件事就是删除@Entity注释。然后更改类名或本机查询名，其中一个是xxxx，另一个是zzzz，这样我就知道运行时在抱怨什么了。

听起来xxxx不应该是实体bean，因为JPA不喜欢在非实体bean中返回结果。您必须只使用SQL字符串调用createNativeQuery。然后调用query.getResultList将结果作为ListObject[]获取，并使用它填充非实体结果bean

几年前，我写了一篇文章，这可能会帮助您使用JPA执行高级本机查询。

听起来xxxx不应该是实体bean，因为JPA不喜欢在非实体bean中返回结果。您必须只使用SQL字符串调用createNativeQuery。然后调用query.getResultList将结果作为ListObject[]获取，并使用它填充非实体结果bean

---

几年前，我写了一篇文章，这可能会帮助您使用JPA执行高级本机查询。

是的，这是可能的，但有点棘手。这里有一个复杂的例子，应该涵盖大多数基础。在本例中：

您有一个具有到期日期的发票对象； 每张发票与一家公司存在多对一关系； 每个发票还与一组项目具有零或一对多关系 以下是模式：

CREATE TABLE "public"."invoice" (
  id SERIAL, 
  company_id int, 
  due_date date, 
  PRIMARY KEY(id)
);
CREATE TABLE "public"."item" (
  id SERIAL, 
  invoice_id int,
  description text,
  PRIMARY KEY(id)
);
CREATE TABLE "public"."company" (
  id SERIAL,
  name text,
  PRIMARY KEY(id)
);

为了完整起见，INVOICE对象非常复杂，例如：

@Entity
@Table(name = "invoice")
@Loader(namedQuery = "loadInvoiceObject")
@NamedNativeQuery(name="loadInvoiceObject",
  query="SELECT " +
        "inv.id," +
        "inv.due_date," +
        "co.*," +
        "it.*," +
        "FROM invoice inv " +
        "JOIN company co ON co.id = inv.company_id " +
        "LEFT OUTER JOIN item it ON it.invoice_id = inv.id " +
        "WHERE inv.id = :id",
  resultSetMapping = "invoicemap")
@SqlResultSetMapping(name = "invoicemap",
  entities = {
    @EntityResult(entityClass = Invoice.class),
    @EntityResult(entityClass = Company.class),
    @EntityResult(entityClass = Item.class)
  }
)
public class Invoice {

  private Integer id;
  private Date dueDate;
  private Company company;
  private List<Item> items = new ArrayList<Item>();

  public Invoice() { /* no-args constructor */ }

  @Id
  @Column(name = "id", nullable = false)
  public Integer getId() { return id; }
  public void setId(Integer id) { this.id = id; }

  @Column(name = "due_date")
  @Temporal(TemporalType.DATE)
  public Date getDueDate() { return dueDate; }
  public void setDueDate(Date dueDate) { this.dueDate = dueDate; }

  @ManyToOne(optional = false)
  @JoinColumn(name = "company_id", nullable = false)
  public Company getCompany() { return company; }
  public void setCompany(Company company) { this.company = company; }

  @OneToMany(mappedBy = "invoice")
  public List<Item> getItems() { return items; }
  public void setItems(List<Item> items) { this.items = items; }

}

该公司反对：

@Entity
@Table(name = "company")
public class Company {

  private Integer id;
  private String name;
  private List<Invoice> invoices = new ArrayList<Invoice>();

  public Company() { /* no-args constructor */ }

  @Id
  @Column(name = "id", nullable = false)
  public Integer getId() { return id; }
  public void setId(Integer id) { this.id = id; }

  @Column(name = "name")
  public String getName() { return name; }
  public void setName(String name) { this.name = name; }

  @OneToMany(mappedBy = "company")
  public List<Invoice> getInvoices() { return invoices; }
  public void setInvoices(List<Invoice> invoices) { this.invoices = invoices; }

}

---

是的，这是可能的，但有点棘手。这里有一个复杂的例子，应该涵盖大多数基础。在本例中：

您有一个具有到期日期的发票对象； 每张发票与一家公司存在多对一关系； 每个发票还与一组项目具有零或一对多关系 以下是模式：

CREATE TABLE "public"."invoice" (
  id SERIAL, 
  company_id int, 
  due_date date, 
  PRIMARY KEY(id)
);
CREATE TABLE "public"."item" (
  id SERIAL, 
  invoice_id int,
  description text,
  PRIMARY KEY(id)
);
CREATE TABLE "public"."company" (
  id SERIAL,
  name text,
  PRIMARY KEY(id)
);

为了完整起见，INVOICE对象非常复杂，例如：

@Entity
@Table(name = "invoice")
@Loader(namedQuery = "loadInvoiceObject")
@NamedNativeQuery(name="loadInvoiceObject",
  query="SELECT " +
        "inv.id," +
        "inv.due_date," +
        "co.*," +
        "it.*," +
        "FROM invoice inv " +
        "JOIN company co ON co.id = inv.company_id " +
        "LEFT OUTER JOIN item it ON it.invoice_id = inv.id " +
        "WHERE inv.id = :id",
  resultSetMapping = "invoicemap")
@SqlResultSetMapping(name = "invoicemap",
  entities = {
    @EntityResult(entityClass = Invoice.class),
    @EntityResult(entityClass = Company.class),
    @EntityResult(entityClass = Item.class)
  }
)
public class Invoice {

  private Integer id;
  private Date dueDate;
  private Company company;
  private List<Item> items = new ArrayList<Item>();

  public Invoice() { /* no-args constructor */ }

  @Id
  @Column(name = "id", nullable = false)
  public Integer getId() { return id; }
  public void setId(Integer id) { this.id = id; }

  @Column(name = "due_date")
  @Temporal(TemporalType.DATE)
  public Date getDueDate() { return dueDate; }
  public void setDueDate(Date dueDate) { this.dueDate = dueDate; }

  @ManyToOne(optional = false)
  @JoinColumn(name = "company_id", nullable = false)
  public Company getCompany() { return company; }
  public void setCompany(Company company) { this.company = company; }

  @OneToMany(mappedBy = "invoice")
  public List<Item> getItems() { return items; }
  public void setItems(List<Item> items) { this.items = items; }

}

该公司反对：

@Entity
@Table(name = "company")
public class Company {

  private Integer id;
  private String name;
  private List<Invoice> invoices = new ArrayList<Invoice>();

  public Company() { /* no-args constructor */ }

  @Id
  @Column(name = "id", nullable = false)
  public Integer getId() { return id; }
  public void setId(Integer id) { this.id = id; }

  @Column(name = "name")
  public String getName() { return name; }
  public void setName(String name) { this.name = name; }

  @OneToMany(mappedBy = "company")
  public List<Invoice> getInvoices() { return invoices; }
  public void setInvoices(List<Invoice> invoices) { this.invoices = invoices; }

}