休眠本机 sql 查询返回

Question

I want to do a native SQL query, which joins 2 Tables.

The return value should be all elements of the District Table, which would be (id, name, district_code, coordinates) , and also a count(*) of all Objects which are in a District (therefore the join with some other table).

So I have all columns of district (district.*) one field which is Count(*) . Which kind of query can I use, so that I can comfortable use it in my java code? I can't add an entity or, because the count(*) wouldn't fit to it!?

I have got a District class which looks like this:

@XmlRootElement
public class District extends AbstractEntity{

    private int id;
    private String name;
    private int district_code;
    @Transient
    private int carsQuantity;

    public District(){}

    @Override
    public int getId() {
        return id;
    }

    @Override
    public void setId(int id) {
        this.id = id;       
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getDistrict_code() {
        return district_code;
    }

    public void setDistrict_code(int district_code) {
        this.district_code = district_code;
    }

    public int getCarsQuantity() {
        return carsQuantity;
    }

    public void setCarsQuantity(int carsQuantity) {
        this.carsQuantity = carsQuantity;
    }
}

My District.hbm.xml:

<hibernate-mapping package="at.opendata.entitys">      
    <class name="District" table="districts">       
        <id name="id" column="id">
            <generator class="increment"/>
        </id>
        <property name="name"/>
        <property name="district_code"/>                
    </class>    
</hibernate-mapping>

EDIT:

I can't do it with HQL oder JPQL, because I need a SUBSELECT in my FROM CLAUSE.

SELECT d.id, count(*) FROM (SELECT cd.coordinates AS coordinates FROM cars AS c LEFT JOIN cardetail AS cd ON (c.car_id = cd.car_id)) AS c CROSS JOIN districts AS d WHERE ST_CONTAINS(d.coordinates, c.coordinates) GROUP BY id

Answer 1

First of all, you don't need a native query for that. JPQL will do just fine. And the result of such a query will simply be a List<Object[]> , where each object array will contain an element for each returned column. Just iterate over this list and do whatever you want with the elements:

for (Object[] row : list) {
    Integer id = (Integer) row[0];
    String name = (String) row[1];
    ...
    Long count = (Long) row[4];
    ...
}