Hibernate之Query接口的uniqueResult()方法

如果查询返回多个值用list()方法

public void testQuery(){
Configuration config = new Configuration().configure();
SessionFactory factory = config.buildSessionFactory(); //创建SessionFactory
Session session = factory.openSession(); //创建Session
session.beginTransaction(); //开始事务

Query query = session.createQuery("from Student");
List list = query.list(); // 用list方法返回多个值
//List list = session.createQuery("from Student").list();
for(int i=0;i<list.size();i++){
Student student = (Student)list.get(i);
System.out.print(student.getId()+" ");
System.out.print(student.getName()+" ");
System.out.print(student.getSex()+" ");
System.out.print(student.getBirthday());
System.out.println();
}

session.getTransaction().commit(); //提交事务
session.close(); //关闭Session
}

当确定返回的实例只有一个或者null时 用uniqueResult()方法


public void testGet(){
Configuration config = new Configuration().configure();
SessionFactory factory = config.buildSessionFactory();
Session session = factory.openSession();
session.beginTransaction();

Query query = session.createQuery("from Student s where s.id=?");
query.setString(0, "2");
Student student = (Student)query.uniqueResult(); //当确定返回的实例只有一个或者null时 用uniqueResult()方法
//Student student = (Student)session.createQuery("from Student s where s.id=?").setString(0,"5").uniqueResult();

System.out.println(student.getName());
System.out.println(student.getBirthday());

session.getTransaction().commit();
session.close();
}