Spring Data JPA 查询部分字段

这里使用的是@Query

@Query(value = "select new OrderDetail (productId,productName,sum(productQuantity) as productQuantity) from OrderDetail where " +
        "TIMESTAMPDIFF(DAY,:time,createTime) = 0 " +
        "group by productId,productName")
List findByCreateTime(@Param("time") String timeStamp);

写这个sql语句必须提供相应的构造方法，默认的构造方法和部分字段的构造方法

实体类

@Data
@Entity
@AllArgsConstructor
@NoArgsConstructor
public class OrderDetail {

    @Id
    private String detailId;

    private String orderId;

    private String productId;

    private String productName;

    private BigDecimal productPrice;

    private Integer productQuantity;

    private String productIcon;

    //创建时间
    private Date createTime;
    //修改时间
    private Date updateTime;

    public OrderDetail(String productId, String productName, Long productQuantity) {
        this.productId = productId;
        this.productName = productName;
        this.productQuantity = Integer.parseInt(productQuantity.toString());
    }
}

因为SUM函数返回的是long,类型，所以我进行了一下转换。