Hibernate连接查询join

主表Owner 从表Tea

Owner及Tea的pojo

import java.util.HashSet;
import java.util.Set;

public class Owner {
private int id;
private String name;
private String Address;
private Set<Tea> set=new HashSet<Tea>();
....}

public class Tea {
private int id;
private int name;
private int sales;
private Owner owener;

......}

1.查询对象：直接查询返回一个符合条件的Object[][]的List

<pre class="java" name="code">

@Test

 public void test10(){

  String hql=" from Owner o join o.set where owner_id = :newName";

  Query query=session.createQuery(hql);

  List<Object[]> list=query.setInteger("newName", 103).list();

  tx.commit();

  Iterator it=list.iterator();

  while(it.hasNext()){

   Object[] o=(Object[]) it.next();

   System.out.print(o[0]);

   System.out.println(o[1]);

  }

 }

结果：

Owner [id=103, name=李华_1, Address=合肥_1]Tea [id=205, name=2, sales=2]
Owner [id=103, name=李华_1, Address=合肥_1]Tea [id=206, name=3, sales=3]

2.查询对象：在查询对象前加上distinct  这时只返回一个符合条件的主表对象的List

@Test
public void test10(){
String hql=" select distinct o from Owner o join o.set where owner_id = :newName";
Query query=session.createQuery(hql);
List<Owner> list=query.setInteger("newName", 103).list();
tx.commit();
Iterator it=list.iterator();
while(it.hasNext()){
System.out.println(it.next().toString());
}
}

查询结果：

</pre></p><pre class="java" name="code">Owner [id=103, name=李华_1, Address=合肥_1]

3.查询属性：查询单个属性时返回一个Object查询多个属性时返回一个Object[][][][]....

distinct可加可不加

@Test
public void test1(){
String hql="select o.name from Owner o inner join o.set teas where teas.name= :a";

Query query=session.createQuery(hql);
query.setString("a","2");
// query.setInteger("b", 4);
List<String> olist=query.list();
tx.commit();
for(String s:olist){
System.out.println(s);
}
}