例如对于TUser类

1.实体查询
String hql = " from TUser";

执行这条语句会返回TUser以及TUser子类纪录
注: 如果 TUser 类具有外键, 查询会报错!
解决思路方法: select 别名.属性 from 类 as 别名. 没有别名.属性仍然报错!


hql = "from java.lang.Object"
会返回数据库中所有库表纪录

where 语句
hql = "from TUser as user where user.name='yyy'";

其中as可以省略也样
hql = "from TUser user where user.name='yyy'";

where子句中我们可以通过比较运算符设定条件如:
=, <>, >, <, >=, <=, between, not between, in, not in, is, like等

2.属性查询
List list = session.createQuery("select user.name, user.age from TUser as user").list;

还可以在HQL中动态构造对象例子思路方法将数据封装
List list = session.createQuery("select TUser(user.name, user.age) from TUser as user").list;
Iterator it = list.iterator;
while(it.hasNext ) {
TUser user = (TUser)it.next;
.out.prln(user.getName);
}
但是要注意这里TUser对象只是对name和age属性封装其他状态均未赋值所以不能用它来进行更新操作

也可以在HQLSelect子句中使用统计
"select count(*) ,min(user.age) from TUser as user"

也可以使用distinct关键字来删除重复纪录
select distinct user.name from TUser as user;

3.实体更新和删除
hibernate 2中需要先查询出实体设置属性后再保存

hibernate 3中提供了更灵活方式(bulk delete/update)
更新:
Query query = session.createQuery("update TUser age=18 where id=1");
query.executeUpdate;
删除:
session.createQuery("delete TUser where age>=18");
query.executeUpdate;

4.分组和排序
Order by子句:
from TUser user order by user.name, user.age desc
Group by子句和Having子句
"select count(user), user.age from TUser user group by user.age having count(user)>10"

5.参数邦定
通过顺序占位符?来填充参数:
1)hibernate 2 中通过session.find思路方法来填充
session.find("from TUser user where user.name=?", "Erica", Hibernate.STRING);
多个参数情况:
Object args = Object {"Erica", Integer(20)};
Type types = Type{Hibernate.STRING, Hibernate.INTEGER};
session.find("from TUser user where user.name=? and user.age=?", args, types);

2)通过Query接口进行参数填充:
Query query = session.createQuery("from TUser user where user.name=? and user.age>?");
query.String(0,"Erica");
query.Integer(1, 20);

通过引用占位符来填充参数:
String hql = "from TUser where name=:name";
Query query = session.createQuery(hql);
query.Parameter("name","Erica");

甚至可以将查询条件封装为个JavaBean
UserQuery {
private String name;
private Integer age;
//getter and ter
}
String hql = "from TUser where name=:name and age=:age";
Query query = session.createQuery(hql);
UserQuery uq = UserQuery;
uq.Name("Erica");
uq.Age( Integer(20));

query.Properties(uq); //会里面getter?
query.iterate;

6.联合查询
也可以使用 inner join,left outer join, right out join, full join
排列组合:form TUser, TAddress