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我有一个关于 Hibernate ManyToOne 关联的问题。

我有一个这样映射的产品实体:

public class Product {
@Id
@DocumentId
@Column(name = "PRODUCT_ID", columnDefinition = "integer")
@Index(name = "PRODUCT_ID_IDX")
private Long id;

@Column(name = "SALE_PRICE")
@Index(name = "PRODUCT_PRICE_IDX")
private Double salePrice;
...
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "CATEGORY_ID", nullable = true)
@Index(name = "PRODUCT_ID_CATEGORY_IDX")
private ProductCategory category;
}

那么你怎么能看到我们与 ProductCategory 表有关系。FK 我们存储在 Product 表中。当我创建按特定类别和价格选择产品的查询时,我有下一个 SQL: select this_.PRODUCT_ID as PRODUCT1_9_1_, this_.BUY_URL as BUY2_9_1_, this_.CATEGORY_ID as CATEGORY15_9_1_, this_.CURRENCY as CURRENCY9_1_, this_.IMAGE_URL as IMAGE4_9_1_, this_.INSTOCK as INSTOCK9_1_, this_.LONG_DESCRIPTION as LONG6_9_1_, this_.NAME as NAME9_1_, this_.RATING as RATING9_1_, this_.RETAIL_PRICE as RETAIL9_9_1_, this_.SALE_PRICE as SALE10_9_1_, this_.SHIPPING as SHIPPING9_1_, this_.SHORT_DESCRIPTION as SHORT12_9_1_, this_.UPC as UPC9_1_, this_.VIEWS as VIEWS9_1_, cat1_.CATEGORY_ID as CATEGORY1_10_0_, cat1_.NAME as NAME10_0_, cat1_.RATING as RATING10_0_, cat1_.VIEWS as VIEWS10_0_, cat1_.VISIBLE as VISIBLE10_0_ from PRODUCT this_ inner join PRODUCT_CATEGORY cat1_ on this_.CATEGORY_ID=cat1_.CATEGORY_ID where ( this_.SALE_PRICE between ? and ? and cat1_.CATEGORY_ID in ( ? ) ) order by this_.NAME asc limit ? offset ?

我的问题是下一个:如何避免两个表的内部连接:Product 和 ProductCategory?

我的标准 DAO 代码: criteria.createAlias("category", "cat"); criteria.add(Restrictions.conjunction() .add(Restrictions.between("salePrice", priceLow, priceHigh)) .add(Restrictions.in("cat.id", categoryIds)));

谢谢。

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1 回答 1

2

线

criteria.createAlias("category", "cat");

确切的意思是:创建与 Category 实体的内部联接。

只需使用

criteria.add(
    Restrictions.conjunction()
        .add(Restrictions.between("salePrice", priceLow, priceHigh))
        .add(Restrictions.in("category.id", categoryIds)));
于 2012-07-09T14:02:26.193 回答