单一属性:
//返回结果集属性列表,元素类型和实体类中的属性类型一致 List students = session.createQuery("select name from Student").list(); for (Iterator iter=students.iterator(); iter.hasNext();) { String name = (String)iter.next(); System.out.println(name); }
多个属性:
//查询多个属性,返回对象数组集合 //数组元素的类型与查询的属性类型一致 //数组的长度与select中查询的属性个数一致 List students = session.createQuery("select id, name from Student").list(); for (Iterator iter=students.iterator(); iter.hasNext();) { Object[] obj = (Object[])iter.next(); System.out.println(obj[0] + ", " + obj[1]); }
多个属性查询,返回Student:
//可以使用hql返回Student对象 //需要提供构造函数 List students = session.createQuery("select new Student(id, name) from Student").list(); for (Iterator iter=students.iterator(); iter.hasNext();) { Student student = (Student)iter.next(); System.out.println(student.getId() + ", " + student.getName()); }
可以使用别名:
// 可以使用别名 List students = session.createQuery("select s.id, s.name from Student s").list(); for (Iterator iter=students.iterator(); iter.hasNext();) { Object[] obj = (Object[])iter.next(); System.out.println(obj[0] + ", " + obj[1]); }
实体对象查询:
//返回Student对象的集合 //可以忽select关键字 List students = session.createQuery("from Student").list(); for (Iterator iter=students.iterator(); iter.hasNext();) { Student student = (Student)iter.next(); System.out.println(student.getName()); }
//返回Student对象的集合 //可以忽select关键字,可以加入别名 List students = session.createQuery("from Student s").list(); for (Iterator iter=students.iterator(); iter.hasNext();) { Student student = (Student)iter.next(); System.out.println(student.getName()); }
//返回Student对象的集合 //如果使用select查询实体对象,必须使用别名 List students = session.createQuery("select s from Student s").list(); for (Iterator iter=students.iterator(); iter.hasNext();) { Student student = (Student)iter.next(); System.out.println(student.getName()); }
条件查询
//可以拼串 List students = session.createQuery("select s.id, s.name from Student s where s.name like ‘%0%‘").list(); for (Iterator iter=students.iterator(); iter.hasNext();) { Object[] obj = (Object[])iter.next(); System.out.println(obj[0] + ", " + obj[1]); }
//可以使用?方式传递参数 //索引从0开始,不同于jdbc从1开始 //值能使用单引号引起来 //List students = session.createQuery("select s.id, s.name from Student s where s.name like ?").list(); // Query query = session.createQuery("select s.id, s.name from Student s where s.name like ?"); // query.setParameter(0, "%0%"); // List students = query.list(); //方法链编程,建议采用此种方式 List students = session.createQuery("select s.id, s.name from Student s where s.name like ?") .setParameter(0, "%0%") .list(); for (Iterator iter=students.iterator(); iter.hasNext();) { Object[] obj = (Object[])iter.next(); System.out.println(obj[0] + ", " + obj[1]); }
//可以采用 :参数名 的方式传递参数 List students = session.createQuery("select s.id, s.name from Student s where s.name like :myname") .setParameter("myname", "%0%") .list(); for (Iterator iter=students.iterator(); iter.hasNext();) { Object[] obj = (Object[])iter.next(); System.out.println(obj[0] + ", " + obj[1]); }
//采用 ?方式,查询学号为1,2,3,4,5的学生 List students = session.createQuery("select s.id, s.name from Student s where s.id in(?, ?, ?, ?, ?)") .setParameter(0, 1) .setParameter(1, 2) .setParameter(2, 3) .setParameter(3, 4) .setParameter(4, 5) .list(); for (Iterator iter=students.iterator(); iter.hasNext();) { Object[] obj = (Object[])iter.next(); System.out.println(obj[0] + ", " + obj[1]); }
//采用 :参数名 方式,查询学号为1,2,3,4,5的学生 List students = session.createQuery("select s.id, s.name from Student s where s.id in(:ids)") .setParameterList("ids", new Object[]{1, 2, 3, 4, 5}) .list(); for (Iterator iter=students.iterator(); iter.hasNext();) { Object[] obj = (Object[])iter.next(); System.out.println(obj[0] + ", " + obj[1]); }
//查询2009-08的学生,可以调用mysql的日期格式化函数 List students = session.createQuery("select s.id, s.name from Student s where date_format(s.createTime, ‘%Y-%m‘)=?") .setParameter(0, "2009-08") .list(); for (Iterator iter=students.iterator(); iter.hasNext();) { Object[] obj = (Object[])iter.next(); System.out.println(obj[0] + ", " + obj[1]); }
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); //查询2009-08-01 到2009-08-20的学生,可以调用mysql的日期格式化函数 List students = session.createQuery("select s.id, s.name from Student s where s.createTime between ? and ?") .setParameter(0, sdf.parse("2009-08-01 00:00:00")) .setParameter(1, sdf.parse("2009-08-20 23:59:59")) .list(); for (Iterator iter=students.iterator(); iter.hasNext();) { Object[] obj = (Object[])iter.next(); System.out.println(obj[0] + ", " + obj[1]); }
时间: 2024-10-21 20:16:45