如何使用hibernate将结果集从mysql映射到pojo？

发布于 2024-12-23 03:17:14 字数 679 浏览 3 评论 0原文

我有一个产品表：

Product
- PId
- Name

ProductPricing
- PPId
- PId
- startDate
- endDate
- price

对于一种产品，可以有多个 ProductPricing 记录。

为了检索产品的当前价格，我使用以下查询：

SELECT PId, Name, price, startDate, endDate
FROM PRODUCT, PRODUCTPRICING
WHERE PRODUCT.PId = givenId AND PRODUCT.PId = PRODUCTPRICING.PId
AND (today() > PRODUCTPRICING.startDate AND today() < PRODUCTPRICING.endDate);

How do I map the result of this query to my POJO using Hibernate ??

我的 Java Product 对象看起来像这样：

Product
- Id
- Name
- ProductPricing Object

ProductPricing
- startDate
- endDate
- price

原文

I have a product table:

Product
- PId
- Name

ProductPricing
- PPId
- PId
- startDate
- endDate
- price

For one product, there can be multiple ProductPricing records.

For retrieving current price for the product, I use the following query:

SELECT PId, Name, price, startDate, endDate
FROM PRODUCT, PRODUCTPRICING
WHERE PRODUCT.PId = givenId AND PRODUCT.PId = PRODUCTPRICING.PId
AND (today() > PRODUCTPRICING.startDate AND today() < PRODUCTPRICING.endDate);

How do I map the result of this query to my POJO using Hibernate ??

my Java Product object looks something like this:

Product
- Id
- Name
- ProductPricing Object

ProductPricing
- startDate
- endDate
- price

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寂寞美少年 2024-12-30 03:17:15

这将给出稍微不同的查询（使用子查询而不是联接），但结果应该是相同的。

@Entity
class Product
{
@Id
int id;
String name;
@Formula("(select pp.price from PRODUCTPRICING pp where pp.PId = id and today() > pp.startDate AND today() < pp.endDate )")
double price;
}

如果您也想将 ProductPricing 映射为 POJO，我认为您不能将其映射为一对一，因为从技术上讲，它是带有过滤器的一对多，希望只产生一个结果。因此，您将拥有 Set。在您的 Product 类中：

<set name="prices" table="PRODUCTPRICING">
  <key column="PId"/>
  <composite-element class="ProductPricing">
    <property name="price"/>
    <property name="startdata"/>
    <property name="enddate"/>
  </composite-element>
  <filter condition="today() > startDate AND today() < endDate"/>
</set>

使用复合元素，您不需要 PRODUCTPRICING 表中的主键 PPId。

This will give a slightly different query (with a sub-query instead of a join), but the result should be the same.

@Entity
class Product
{
@Id
int id;
String name;
@Formula("(select pp.price from PRODUCTPRICING pp where pp.PId = id and today() > pp.startDate AND today() < pp.endDate )")
double price;
}

If you want to map the ProductPricing as a POJO, too, I think you can't map it as a one-to-one, since it's technically a one-to-many with a filter which will hopefully result in only one result. So you'll have a Set<ProductPricing> in your Product class:

<set name="prices" table="PRODUCTPRICING">
  <key column="PId"/>
  <composite-element class="ProductPricing">
    <property name="price"/>
    <property name="startdata"/>
    <property name="enddate"/>
  </composite-element>
  <filter condition="today() > startDate AND today() < endDate"/>
</set>

With composite-element, you don't need a primary key PPId in the PRODUCTPRICING table.

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