無法將每個組的最大N的SQL轉換爲HQL

Question

我在Oracle中有兩個表，分別是product和product_image。顧名思義，他們必須從product到product_image.

的product實體一個一對多的關係：

@Entity 
@Table(name = "PRODUCT", catalog = "", schema = "WAGAFASHIONDB") 
public class Product implements java.io.Serializable 
{ 
    private static final long serialVersionUID = 1L; 
    @Id 
    @Basic(optional = false) 
    @Column(name = "PROD_ID", nullable = false, precision = 35, scale = 0) 
    @SequenceGenerator(name = "productIdSequence", sequenceName = "PRODUCT_SEQ", allocationSize=1, initialValue=1) 
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "productIdSequence") 
    private Long prodId; 
    @Column(name = "PROD_NAME", length = 50) 
    private String prodName; 
    @Column(name = "PROD_CODE", length = 50) 
    private String prodCode; 
    @Lob 
    @Column(name = "PROD_DESC") 
    private String prodDesc; 
    @Basic(optional = false) 
    @Column(name = "MARKET_PRICE", nullable = true, precision = 35, scale = 2) 
    private BigDecimal marketPrice; 
    @Basic(optional = false) 
    @Column(name = "SALE_PRICE", nullable = true, precision = 35, scale = 2) 
    private BigDecimal salePrice; 
    @Column(name = "PROD_FEATURED") 
    private Short prodFeatured; 
    @Column(name = "EXPRESS_DELIVERY") 
    private Short expressDelivery; 
    @Basic(optional = false) 
    @Column(name = "PROD_WEIGHT", nullable = true, precision = 35, scale = 2) 
    private BigDecimal prodWeight; 
    @Column(name = "PROD_OCCASSION", length = 50) 
    private String prodOccassion; 
    @Basic(optional = false) 
    @Column(name = "QTY_AVAILABLE", nullable = true) 
    private BigInteger qtyAvailable; 
    @Column(name = "LATEST") 
    private Short latest; 
    @Column(name = "VISIBLE") 
    private Short visible; 
    @JoinTable(name = "PRODUCT_SIZE", joinColumns = { 
     @JoinColumn(name = "PROD_ID", referencedColumnName = "PROD_ID")}, inverseJoinColumns = { 
     @JoinColumn(name = "SIZE_ID", referencedColumnName = "SIZE_ID")}) 
    @ManyToMany(fetch = FetchType.LAZY) 
    private Set<SizeTable> sizeTableSet; 
    @ManyToMany(mappedBy = "productSet", fetch = FetchType.LAZY) 
    private Set<Colour> colourSet; 
    @OneToMany(mappedBy = "prodId", fetch = FetchType.LAZY) 
    private Set<Measurement> measurementSet; 
    @OneToMany(mappedBy = "prodId", fetch = FetchType.LAZY) 
    private Set<Wish> wishSet; 
    @OneToMany(mappedBy = "prodId", fetch = FetchType.LAZY) 
    private Set<Cart> cartSet; 



    @OneToMany(mappedBy = "prodId", fetch = FetchType.LAZY) 
    private Set<ProductImage> productImageSet;    //<-------- 



    @OneToMany(cascade = CascadeType.ALL, mappedBy = "product", fetch = FetchType.LAZY) 
    private Set<OrderItem> orderItemSet; 
    @JoinColumn(name = "SUB_CAT_ID", referencedColumnName = "SUB_CAT_ID") 
    @ManyToOne(fetch = FetchType.LAZY) 
    private Subcategory subCatId; 
    @JoinColumn(name = "FABRIC_ID", referencedColumnName = "FABRIC_ID", nullable = false) 
    @ManyToOne(optional = false, fetch = FetchType.LAZY) 
    private Fabric fabricId; 
    @JoinColumn(name = "BRAND_ID", referencedColumnName = "BRAND_ID") 
    @ManyToOne(fetch = FetchType.LAZY) 
    private Brand brandId; 
    @OneToMany(mappedBy = "prodId", fetch = FetchType.LAZY) 
    private Set<Inquiry> inquirySet; 
    @OneToMany(mappedBy = "prodId", fetch = FetchType.LAZY) 
    private Set<Rating> ratingSet; 
} 

的ProductImage實體：

@Entity 
@Table(name = "PRODUCT_IMAGE", catalog = "", schema = "WAGAFASHIONDB") 
public class ProductImage implements java.io.Serializable 
{ 
    private static final long serialVersionUID = 1L; 
    @Id 
    @Basic(optional = false) 
    @Column(name = "PROD_IMAGE_ID", nullable = false, precision = 35, scale = 0) 
    @SequenceGenerator(name = "productIdSequence", sequenceName = "PRODUCT_IMAGE_SEQ", allocationSize=1, initialValue=1) 
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "productIdSequence") 
    private Long prodImageId; 
    @Lob 
    @Column(name = "PROD_IMAGE") 
    private String prodImage; 
    @JoinColumn(name = "PROD_ID", referencedColumnName = "PROD_ID") 



    @ManyToOne(fetch = FetchType.LAZY) 
    private Product prodId;   //<-------------- 
} 

我需要獲取的資料列ProductImage的每組行（實際上每組產品）的最大值prodId，即每組最大的N個。

Oracle本機SQL可按如下方式構建。

SELECT pi.prod_image_id, pi.prod_id, pi.prod_image 
FROM product_image pi 
INNER JOIN (select max(pi.prod_image_id) AS prod_image_id, pi.prod_id FROM product_image pi GROUP BY pi.prod_id) prod_image 
ON pi.prod_image_id=prod_image.prod_image_id 

這與預期的完全相同，但我無法將此SQL轉換爲HQL。試圖直接在createQuery()方法中作爲HQL執行時會導致QuerySyntexException，第一個圓括號處的意外令牌。您能否給我一個提示將此SQL轉換爲HQL？

---

編輯：

一些問題，如下面還沒有回答做到這一點，因爲它實際上意味着：

• Best way to use hibernate for complex queries like top n per group
• hql query to retrieve top n from each group
• Using HQL with MySQL how can I order the result set before the group by so the right record is picked?

我想，在Hibernate中通過HQL無法實現這一點。我可能需要使用某些DTO類將此SQL分解爲適當的兩個或多個HQL語句。如果可以通過像上面的SQL這樣的單個HQL語句，那麼請不要忘記在這裏回答，因爲我在和我的應用程序中有很多地方有這樣的要求。

Answer 1

看看這個：

select 
    pi.prodImageId, 
    pi.prodId 
from 
    ProductImage pi 
where 
    pi.prodImageId in (
    select max(pis.prodImageId) 
    from Product p 
     inner join p.productImageSet pis 
    group by p.prodId 
) 

翻譯爲：

select 
    productima0_.prodImageId as col_0_0_, 
    productima0_.prodId_prodId as col_1_0_, 
    product1_.prodId as prodId18_, 
    product1_.name as name18_ 
from 
    ProductImage productima0_ 
inner join 
    Product product1_ on productima0_.prodId_prodId=product1_.prodId 
where 
    productima0_.prodImageId in (
     select max(productima3_.prodImageId) 
     from 
     Product product2_ inner join ProductImage productima3_ on product2_.prodId=productima3_.prodId_prodId 
     group by product2_.prodId 
    ) 

這是你想要我猜猜是什麼？