Question

我有一个自定义对象

@Component
public class SaleReport {

    private Date date;
    private String customerName;
    private String phoneNo;
    private String productName;
    private Integer quantity;
    private Double totalAmount;

    public Date getDate() {
        return date;
    }

    public void setDate(Date date) {
        this.date = date;
    }

    public String getCustomerName() {
        return customerName;
    }

    public void setCustomerName(String customerName) {
        this.customerName = customerName;
    }

    public String getPhoneNo() {
        return phoneNo;
    }

    public void setPhoneNo(String phoneNo) {
        this.phoneNo = phoneNo;
    }

    public String getProductName() {
        return productName;
    }

    public void setProductName(String productName) {
        this.productName = productName;
    }

    public Integer getQuantity() {
        return quantity;
    }

    public void setQuantity(Integer quantity) {
        this.quantity = quantity;
    }

    public Double getTotalAmount() {
        return totalAmount;
    }

    public void setTotalAmount(Double totalAmount) {
        this.totalAmount = totalAmount;
    }
}

我需要使用JpaRepository<Sale, Integer>返回此对象的列表 SaleRepository如下：

@Repository
public interface SaleRepository extends JpaRepository<Sale, Integer> {


    @Query(value = "SELECT B.order_date AS date, E.customer_name AS customerName, " +
            "E.phone_no AS phoneNo, D.product_name AS productName, C.quantity AS quantity, " +
            "C.total_price AS totalAmount " +
            "FROM SALE A " +
            "INNER JOIN A.quotation_id B " +
            "INNER JOIN B.quotation_id C " +
            "INNER JOIN C.product_id D " +
            "INNER JOIN B.customer_id E " +
            "WHERE (B.order_date BETWEEN :from_date AND :to_date)", nativeQuery = true)
    public List<SaleReport> getSaleReportByDate(@Param("from_date")String fromDate, @Param("to_date")String toDate);

}

这是我的Controller方法：

@GetMapping("api/report/sale/{from_date}/{to_date}")
        public List<SaleReport> getSaleReportByDate(@PathVariable("from_date") String fromDate, @PathVariable("to_date") String toDate){
        return saleRepository.getSaleReportByDate(fromDate, toDate);
}

当我运行代码时，它显示此错误：

com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown database 'a'
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_161]
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_161]
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_161]
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_161]
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:425) ~[mysql-connector-java-5.1.47.jar:5.1.47]
    at com.mysql.jdbc.Util.getInstance(Util.java:408) ~[mysql-connector-java-5.1.47.jar:5.1.47]
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:944) ~[mysql-connector-java-5.1.47.jar:5.1.47]

我的数据库名称很好。当我要求其他方法时，它可以完美工作。请给我建议一个理想的解决方案。

Answer 1

1），您需要为SaleReport类创建一个构造函数，该构造函数接受select语句中使用的所有参数，并按其确切顺序接受。 >

2）：更改查询，以便用new语句包装所选列：

@Query(value = "SELECT new org.mypackage.SaleReport(B.order_date AS date,"
                        + "E.customer_name AS customerName, "
                        + "E.phone_no AS phoneNo, D.product_name AS productName, 
                        + "C.quantity AS quantity, " +
                        + "C.total_price AS totalAmount) " +
            "FROM SALE A " +
            "INNER JOIN A.quotation B " +
            "INNER JOIN B.quotation C " +
            "INNER JOIN C.product D " +
            "INNER JOIN B.customer E " +
            "WHERE (B.order_date BETWEEN :from_date AND :to_date)")

3）我认为您在这里不需要本机查询，您可以直接使用HQL（更改的联接）。

Answer 2

Spring有一个名为@SqlResultSetMapping的注释此注释可以用于上述问题。可以从以下链接找到有关此批注的详细信息：

Annotation Type ConstructorResult

这实际上是将休眠查询结果映射到普通的POJO类中。那就是实际需要的东西。

Example:

   Query q = em.createNativeQuery(
      "SELECT c.id, c.name, COUNT(o) as orderCount, AVG(o.price) AS avgOrder " +
      "FROM Customer c, Orders o " +
      "WHERE o.cid = c.id " +
      "GROUP BY c.id, c.name",
      "CustomerDetailsResult");

   @SqlResultSetMapping(
       name="CustomerDetailsResult",
       classes={
          @ConstructorResult(
               targetClass=com.acme.CustomerDetails.class,
                 columns={
                    @ColumnResult(name="id"),
                    @ColumnResult(name="name"),
                    @ColumnResult(name="orderCount"),
                    @ColumnResult(name="avgOrder", type=Double.class)
                    }
          )
       }
      )

将@SqlResultSetMapping放入任何@Entity的顶部，并确保从数据库返回的datatype与您的POJO类datatype相同。

希望这会对您有所帮助。享受:)

Answer 3

我希望这个答案对您有帮助！

销售是您的实体类，而 SaleReport是pojo 类。

public List<SaleReport> getSaleReportByDate(@Param("from_date")String fromDate, @Param("to_date")String toDate);

您不能从数据库返回pojo类列表，而是返回实体类列表。使用公共列表而不是公共列表

public List<Sale> getSaleReportByDate(@Param("from_date")String fromDate, @Param("to_date")String toDate);

@Repository
public interface SaleRepository extends JpaRepository<**Sale**, Integer>

您必须将实体类列表映射到POJO类列表。

将实体类列表映射到pojo类列表： 由于仍有许多方法可以实现这一目标最简单的解决方案是遍历实体类并将实体属性设置为pojo属性：

我不建议使用构造函数，因为有时您可能只想设置几个字段，而不是POJO类的所有字段。

Arraylist<SaleReport> sr = new Arraylist<SaleReport>();
ArrayList<Sale> saleEntityList= saleRepository.getSaleReportByDate(fromDate,toDate);
for(Sale  s : saleEntityList){
    saleReport = new SaleReport();
    saleReport.setDate(s.getDate);
    //same for all attributes
    sr.add(saleReport);
} 
return sr;

这是您的POJO列表。

需要使用JPA @Query

3 个答案: