hibernate_查询简介: 分页, 数据总数, 结果集的包装, 位置参数的设置

//使用原生sql 查询 employee 表中以"T"或"A"开头的数据
@Test
public void testSql(){
Session session = HibernateUtil.getInstance().getSession();

NativeQuery query = session.createNativeQuery("SELECT * FROM EMPLOYEE WHERE name LIKE ? OR name LIKE ?");
query.setParameter(0, "T%");
query.setParameter(1, "A%");
List<Object> l = query.list();
for(Object o : l){
System.out.println(Arrays.toString((Object[])o));
}

session.close();
}

//使用hql 查询 employee 表中以"T"或"A"开头的数据
@Test
public void testHql(){
Session session = HibernateUtil.getInstance().getSession();

List<Employee> l = session.createQuery("SELECT e FROM Employee e WHERE e.name LIKE ? OR e.name LIKE ?")
.setParameter(0, "T%")
.setParameter(1, "A%")
.list();
for(Employee e : l){
System.out.println(e);
}

session.close();
}

@Test
public void testCri(){
Session session = HibernateUtil.getInstance().getSession();

List<Employee> l = session.createCriteria(Employee.class)
.add(Restrictions.or(
Restrictions.like("name", "T", MatchMode.START),
Restrictions.like("name", "A", MatchMode.START)))
.list();
for(Employee e : l){
System.out.println(e);
}

session.close();
}

//分页
@Test
public void testPage(){
int currentPage = 2;//第几页数据
int pageSize = 3;//每页多少条数据

Session session = HibernateUtil.getInstance().getSession();

//limit ?, ?
List<Employee> l = session.createQuery("FROM Employee")
.setFirstResult((currentPage-1)*pageSize)
.setMaxResults(pageSize)
.list();
for(Employee e : l){
System.out.println(e);
}

session.close();
}

//查询总数
@Test
public void testTotalCount(){
Session session = HibernateUtil.getInstance().getSession();

//select count(*) from employee
//		List l = session.createQuery("SELECT COUNT(e) FROM Employee e").list();
//		System.out.println(l.get(0));
Long total = (Long) session.createQuery("SELECT COUNT(e) FROM Employee e").uniqueResult();
System.out.println(total);
session.close();
}

//查询所有员工的名字
@Test
public void testResult(){
Session session = HibernateUtil.getInstance().getSession();

List<String> l = session.createQuery("SELECT e.name FROM Employee e").list();
System.out.println(l);

session.close();
}

//查询所有员工的id, 名字(返回Object[]集合)
@Test
public void testResult2(){
Session session = HibernateUtil.getInstance().getSession();

List<Object[]> l = session.createQuery("SELECT e.id,e.name FROM Employee e").list();
for(Object[] o : l){
System.out.println(Arrays.toString(o));
}

session.close();
}

//查询员工的所属部门(Department)
@Test
public void testResult3(){
Session session = HibernateUtil.getInstance().getSession();

List<Department> l = session.createQuery("SELECT e.dept FROM Employee e").list();
for(Department d : l){
System.out.println(d);
}

session.close();
}

//查询员工所在部门的地址的街道
@Test
public void testResult4(){
Session session = HibernateUtil.getInstance().getSession();

List<String> l = session.createQuery("SELECT e.dept.address.street FROM Employee e").list();
for(String s : l){
System.out.println(s);
}

session.close();
}

/**
* 结果集的包装
*/
@Test
public void testResult5(){
Session session = HibernateUtil.getInstance().getSession();

List<Object[]> l = session.createQuery("SELECT e.id,e.name,e.dept.id,e.dept.name FROM Employee e").list();
List<Object[]> l2 = session.createQuery("SELECT NEW LIST(e.id,e.name,e.dept.id,e.dept.name) FROM Employee e").list();
List<Object[]> l3 = session.createQuery("SELECT NEW MAP(e.id,e.name,e.dept.id,e.dept.name) FROM Employee e").list();
List<Object[]> l4 = session.createQuery("SELECT NEW MAP(e.id as eid,e.name as ename,e.dept.id as did,e.dept.name as dname) FROM Employee e").list();

//可以在xxx.hbm.xml 文件中为 cd.itcast.day4.extend.ResultValue 取别名,如下:
//<import class="cd.itcast.day4.extend.ResultValue" rename="ResultValue"/>
List<ResultValue> l5 = session.createQuery("SELECT NEW cd.itcast.day4.extend.ResultValue(e.id,e.name,e.dept.id,e.dept.name)").list();

session.close();
}

/**
* =============================== HQL 中的位置参数================
*/
//使用位置参数查询名字首字母是"T"或"A"的员工
@Test
public void testResult6(){
Session session = HibernateUtil.getInstance().getSession();

List<Employee> l = session.createQuery(
"SELECT e FROM Employee e WHERE e.name LIKE :param1 OR e.name LIKE :param2")
.setParameter("param1", "T%")
.setParameter("param2", "A%")
.list();

session.close();
}

//查询所属部门为市场部和技术部的所有员工
@Test
public void testResult7(){
Session session = HibernateUtil.getInstance().getSession();

List<Employee> l = session.createQuery(
"SELECT e FROM Employee e WHERE e.dept.name in(:params)")
.setParameterList("params", new String[]{"市场部", "技术部"})
.list();

session.close();
}

//需求: 查询和某员工同一个部门的所有员工(不确定部门的主键是不是复合主键)
//解决方案: 直接比较部门实体, 让hibernate 去拼接主键.
@Test
public void testResult8(){
Session session = HibernateUtil.getInstance().getSession();

Department d = session.get(Department.class, 1L);

List<Employee> l = session
.createQuery("SELECT e FROM Employee e WHERE e.dept = :param")
.setParameter("param", d)
.list();

session.close();
}