[英]Hibernate custom query on Maps generates unwanted subqueries
我有一堂課,里面有地圖。
@Entity
public class Purchase {
@Id
@GeneratedValue(strategy= GenerationType.IDENTITY)
private Integer purchaseId;
@ManyToOne
@JoinColumn(name = "customer_id")
private User customer;
@ManyToOne
@JoinColumn(name = "item_id")
private Item item;
private String customization;
@ElementCollection
@MapKeyEnumerated(value = EnumType.STRING)
@CollectionTable(name = "purchase_status")
@MapKeyColumn(name = "status")
@Column(name = "date")
private Map<PurchaseStatus, Date> statusTransitions = new HashMap<>();
private Date expectedDeliveryDate;
@ManyToOne
@JoinColumn(name = "purchase_cart_id")
@JsonIgnore
private PurchaseCart purchaseCart;
@OneToOne
@JoinColumn(name = "destination_address_id")
private DestinationAddress destinationAddress;
@Transient
@JsonIgnore
private Date purchaseDate;
它代表購買。 PurchaseStatus是一個枚舉器。 statusTransitions代表此購買獲得的所有狀態。 特別是可以是“ READY_TO_BE_PAID”和“ PAID”。 狀態具有它的相對日期,即地圖的VALUE,狀態本身就是地圖的KEY,因為購買只能處於一次精確的狀態。 我想從數據庫中獲取所有帶有特定用戶(用戶名,這是用戶的屬性)的購買,以及statusTransitions HashMap中具有特定(鍵,值)對的所有購買。 特別是我想創建一個查詢,該查詢返回日期(VALUE)在兩個日期(fromDate和toDate)之間並且PurchaseStatus(KEY)等於枚舉值“ READY_TO_BE_PAID”的所有購買。
我創建了這個自定義查詢:
@Query("select p from Purchase p JOIN p.customer c JOIN p.statusTransitions s WHERE c.username = :username and " +
"(KEY(s) = 'READY_TO_BE_PAID' and " +
"VALUE(s) >= :fromDate and " +
"VALUE(s) <= :toDate)")
List<Purchase> findByUsernameAndByDate(@Param("fromDate") Date fromDate, @Param("toDate") Date toDate, @Param("username") String username);
唯一的問題是生成的SQL查詢如下:
select
*
from
purchase purchase0_
inner join user user1_ on purchase0_.customer_id=user1_.user_id
inner join purchase_status statustran2_ on purchase0_.purchase_id=statustran2_.purchase_purchase_id
where
statustran2_.status='READY_TO_BE_PAID' and
user1_.username=? and
(select
statustran2_.date
from
purchase_status statustran2_
where
purchase0_.purchase_id=statustran2_.purchase_purchase_id
)>=? and
(select
statustran2_.date
from
purchase_status statustran2_
where
purchase0_.purchase_id=statustran2_.purchase_purchase_id
)<=?
這不是我想要的。 它生成兩個子查詢,結果是拋出此錯誤:
java.sql.SQLException: Subquery returns more than 1 row
那是因為當它執行子查詢時,它不會過濾PurchaseStatus上的行,以這種方式返回的行多於一行。 關鍵是我不知道如何重寫查詢以避免這兩個子查詢或將WHERE子句放入此(KEY(s)='READY_TO_BE_PAID')條件。 我發現其他人也遇到了同樣的問題,但找不到任何解決方案。
我找到了解決方案! 看來,當您有此查詢
SELECT p
FROM Purchase p
JOIN p.customer c
JOIN p.statusTransitions s
statusTransactions映射的別名“ s”已經是值,而不是導致您相信的對(鍵,值)。 這有點直觀,因為KEY返回鍵,但是VALUE不返回值,而是自動生成一個子查詢,這不可避免地導致您出錯。
java.sql.SQLException: Subquery returns more than 1 row
因此,正確的方式來重寫它:
SELECT p
FROM Purchase p
JOIN p.customer c
JOIN p.statusTransitions s
WHERE
c.username = :username and
KEY(s) = 'READY_TO_BE_PAID' and
VALUE(s) >= :fromDate and
VALUE(s) <= :toDate
是:
SELECT p
FROM Purchase p
JOIN p.customer c
JOIN p.statusTransitions s
WHERE
c.username = :username and
KEY(s) = 'READY_TO_BE_PAID' and
s >= :fromDate and
s <= :toDate
或者更緊湊:
SELECT p
FROM Purchase p
JOIN p.customer c
JOIN p.statusTransitions s
WHERE
c.username = :username and
KEY(s) = 'READY_TO_BE_PAID' and
s BETWEEN :fromDate and :toDate
正如我已經說過的,別名's'已經是(key,value)對的值!
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