Hibernate - 从多个表到一个对象的复杂查询

Question

我有一个跨越 7 个表的复杂查询，想知道如何在 Hibernate 中实现它。

我目前的尝试是使用 session.createSQLQuery 进行查询，并将结果映射到特定实体。

我不知道该怎么做，因为过去我只使用一个表到一个实体。我需要在哪里指定我想使用可以跨越多个表的复杂查询？那只在我的代码中吗？我的 hbm.xml 文件？除了我目前的尝试之外，我想不出其他任何东西。

这是我的查询示例：

String stringQuery = 
        "select  WI.Customer_Id, CU.Card, CU.Code, "+
                "PI.Identity_Card, PI.Name, PI.Surname, PI.Gender, "+
                "AD.Zip, AD.Geo_Lat, AD.Geo_Long, "+
                "CO.City_Geo_Level, "+
                "CU.Address_id, CA.Name, "+
                "CU.Category_Id, "+
                "CU.Status, "+
                "Sum(MO.Charged_Points) as Charged_Points, "+
                "Sum(MO.Total_Money) as Total_Money, "+
                "Count(MO.id) as AmountTransWinner "+
        "from Promotions_Winner WI "+ 
        "join Customers CU "+
          "on WI.Customer_id = CU.id "+
        "join Personal_Info PI "+
          "on CU.Personal_Info_Id = PI.id "+
        "join Address AD "+
          "on CU.Address_Id = AD.id "+
        "join Countries CO "+
          "on AD.country_id = CO.id "+
        "join Campaigns CA "+
          "on CU.Campaign_Id = CA.id "+
        "join Movements MO "+
          "on WI.Movement_Id = MO.id "+
        "where WI.Promotion_Id = :pPromotionID "+
        "group by "+
          "WI.Customer_Id, CU.Card, CU.Fidely_Code, "+
          "PI.Identity_Card, PI.Name, PI.Surname, PI.Gender, "+
          "AD.Zip, AD.Geo_Lat, AD.Geo_Long, "+
          "CO.City_Geo_Level, "+
          "CU.Address_id, CA.Name, "+
          "CU.Category_Id, "+
          "CU.Status";

Answer 1

您不需要 SQL 来执行此查询。 HQL 会做得很好。而这样的查询返回一个List<Object[]>，每个Object[] 包含一行结果集。因此，您将在索引 0 处找到客户 ID，在索引 1 处找到卡片等。您只需遍历行并在每次迭代时创建轻量级对象的实例。

见http://docs.jboss.org/hibernate/core/3.6/reference/en-US/html_single/#queryhql-select

Answer 2

据我所知，这是 7 个表的连接。如果您使用的是休眠，您会将这些表中的每一个映射到实体，然后使用 @JoinColumn 映射到它的每个依赖项。这是hibernate用来防止发生的那种SQL查询。

Answer 3

我终于可以用这段代码解决了：

String stringQuery = 
                "select " +
                        "CU.Card as card, " +
                        "CU.Fidely_Code as fidelyCode, "+
                        "PI.Identity_Card as identityCard, " +
                        "PI.Name as name, " +
                        "PI.Surname as surname, " +
                        "PI.Gender as gender, "+
                        "AD.Zip as zip, " +
                        "AD.Geo_Lat as geo_lat, " +
                        "AD.Geo_Long as geo_long, "+
                        "CO.City_Geo_Level as cityGeoLevel, "+
                        "CA.Name as campaignName, "+
                        "CU.Status as status, "+
                        "Sum(MO.Charged_Points) as pointsCharged, "+
                        "Sum(MO.Total_Money) as amountPurchase, "+
                        "Count(MO.id) as amountTransWinner "+
                "from Promotions_Winner WI "+ 
                "join Customers CU "+
                  "on WI.Customer_id = CU.id "+
                "join Personal_Info PI "+
                  "on CU.Personal_Info_Id = PI.id "+
                "join Address AD "+
                  "on CU.Address_Id = AD.id "+
                "join Countries CO "+
                  "on AD.country_id = CO.id "+
                "join Campaigns CA "+
                  "on CU.Campaign_Id = CA.id "+
                "join Movements MO "+
                  "on WI.Movement_Id = MO.id "+
                "where WI.Promotion_Id = :pPromotionID "+
                "group by "+
                  "WI.Customer_Id, CU.Card, CU.Fidely_Code, "+
                  "PI.Identity_Card, PI.Name, PI.Surname, PI.Gender, "+
                  "AD.Zip, AD.Geo_Lat, AD.Geo_Long, "+
                  "CO.City_Geo_Level, "+
                  "CU.Address_id, CA.Name, "+
                  "CU.Category_Id, "+
                  "CU.Status ";

        //Query query = this.getSession().createSQLQuery(stringQuery).addEntity("", PromotionsWinnerLittle.class);
        //Query query = this.getSession().createSQLQuery(stringQuery).setResultSetMapping("PromotionsWinnerLittle");
        Query query = this.getSession().createSQLQuery(stringQuery)
            .addScalar("card", StandardBasicTypes.LONG)
            .addScalar("fidelyCode", StandardBasicTypes.LONG)
            .addScalar("identityCard", StandardBasicTypes.STRING)
            .addScalar("name", StandardBasicTypes.STRING)
            .addScalar("surname", StandardBasicTypes.STRING)
            .addScalar("gender", StandardBasicTypes.STRING)
            .addScalar("zip", StandardBasicTypes.STRING)
            .addScalar("geo_lat", StandardBasicTypes.BIG_DECIMAL)
            .addScalar("geo_long", StandardBasicTypes.BIG_DECIMAL)
            .addScalar("cityGeoLevel", StandardBasicTypes.LONG)
            .addScalar("campaignName", StandardBasicTypes.STRING)
            .addScalar("status", StandardBasicTypes.LONG)
            .addScalar("pointsCharged", StandardBasicTypes.BIG_DECIMAL)
            .addScalar("amountPurchase", StandardBasicTypes.LONG)
            .addScalar("amountTransWinner", StandardBasicTypes.LONG)            
            .setResultTransformer(Transformers.aliasToBean(PromotionsWinnerLittle.class));

        //Query query = this.getSession().createSQLQuery(stringQuery);

        query = query.setLong("pPromotionID", promotionID);

        List lista = query.list();

我刚刚在 Select 和 addScalar + setResultTransformer 上添加了“As”部分

Answer 4

他们有两种方法可以做到这一点。

1.你会得到一个列表对象数组。

 List<Object[]>

这里数组的一个元素代表你的查询的一行。

2.您可以使用休眠功能ResultTransformer - 为查询的输出创建一个简单的类。 - 创建一个 ResultTransformer。

例如

 public class MyResultTransformer implements ResultTransformer {


/*
Method to convert to generic type list
*/
    @Override
    public List<Employee> transformList(List arg0) {
        List<Employee> employees = new ArrayList<Employee>();
        for (Object employee : arg0) {
            employees.add((Employee) employee);
        }
        return employees;
    }

    /*
    Code to transform your query output to Object
    */
    @Override
    public Employee transformTuple(Object[] arg0, String[] arg1) {
        System.out.println("MyResultTransformer.transformTuple()");
        Employee tempEmp = new Employee();
        tempEmp.setEmployee_id((BigInteger) arg0[0]);
        return tempEmp;
    }
}

- 为查询设置转换器。

Query query=session.createSQLQuery("SELECT * FROM employeedetail"); // You can use named query, SQL native also
      query.setResultTransformer(new MyResultTransformer());
          List<Employee> employees=query.list();