经典hql语句
4.hql多表查询
(1)String hql = "select new map(a.CUId as CUId,a.unitName as unitName,b.CUFId as CUFId,b.UFName as UFName) from PhCorrelativeUnit a,PhCorrelativeUnitFunction b where a.CUId=b.CUId";
List list = this.getHibernateTemplate().find(hql);
多个表的字段放到map中,map的键值就是as后面的别名,如果没有as就是字段名
(2) String hql = "select new com.phantom.appeal.action.bean.DealPaper(a.id as id,a.billId as billId,a.state as???? state,a.creator as creator,a.createtime as createtime ,b.eventContent as eventContent ,c.realName as???? realName,b.billCode as billCode,b.citName as citName ) from PhDealBill a,PhAcceptBill b,PhUser c where??? a.departmentId="+ billid+ " and a.state=0 and a.billId=b.billId and a.creator =c.userId order by a.billId";
return this.getHibernateTemplate().find(hql);
另外就是写一个类,对应你要查询的字段,这里的类名是new com.phantom.appeal.action.bean.DealPaper,里面对应查询的字段名
5.得到记录数
String hql = "select count(*) from PhUser";
List list = this.getHibernateTemplate().find(hql);
return ((Long) list.get(0)).intValue();
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五种检索方式的使用场合和特点：
HQL ： 是面向对象的查询语言，同SQL有些相似是Hib中最常用的方式。
?????? 查询设定各种查询条件。
?????? 支持投影查询，检索出对象的部分属性。
?????? 支持分页查询，允许使用having和group by
?????? 提供内制的聚集函数，sum()，min()，max()
?????? 能调用用户的自定义SQL
?????? 支持子查询，嵌入式查询
?????? 支持动态绑定参数
建议使用Query接口替换session的find方法。
?? Query Q = session.createQuery("from customer as c where c.name = :customerName" + "and c.age = :customerAge");
?? query.setString ("customerName" , "tom");
?? query.setInteger("customerAge" , "21");
?? list result = query.list();
QBC : QBCAPI提供了另一种方式，主要是Criteria接口、Criterion接口和Expression类
?? Criteria criteria = session.createCriteria(customer.class);
?? Criterion criterion1 = Expression.like("name","t%");
?? Criterion criterion2 = Expression.eq("age",new Integer(21));
?? Critera = criteria.add(criterion1) ;
?? Critera = criteria.add(criterion2) ;
?? list result = criteria.list();
?? 或是： list result = session.createCriteria(Customer.class).add(Expression.eq("this.name","tom")).list();
SQL : 采用HQL和QBC检索时，Hib生成SQL语句适用所有数据库。
?? Query query = session.createSQLQuery("select {c.*} from customers c where c.name like : customername " + "and c.age = :customerage","c",customer.calss);
?? query.setString("customername","tom");
?? query.setInteger("customerage","21");
?? list result = query.list();
/////////////多态查询
?? HQL ：session.createQuery("from employee");
?? QBC ：session.createCriteria(employee.class);
?? HQL : session.createQuery("from hourlyEmployee");
?? QBC : session.createCriteria(hourlyEmployee.class);
?? 下面的HQL查询语句将检索出所有的持久化对象：
?? from java.lang.Object ;
?? from java.io.serializable ;
////////////查询的排序
?? 1'查询结果按照客户姓名升序排列：
?? HQL ：
??????? Query query = session.createQuery ("from customer c order by c.name");
?? QBC ：
??????? Criteria criteria = session.createCriteria(customer.class);
??????? criteria.addOrder(order.asc("name"));
?? HQL :
??????? Query query = session.createQuery ("from customer c order by c.name asc , c.age desc");
?? QBC :
??????? Criteria criteria = session.createCriteria(customer.class);
??????? criteria.addOrder(order.asc ("name"));
??????? criteria.addOrder(order.desc("age"));
??????? import net.sf.hibernate.pression.Order
??????? import mypack.Order
??????? ...........
??????? Criteria criteria = session.createCritria (mypack.Order.class);
??????? criteria.addOrder(net.sf.hibernate.Order.asc("name"));
///////////HQL语句的参数绑定Query接口提供了绑定各种Hib映射类型的方法。
??????? setBinary()
??????? setString()
??????? setBoolean()
??????? setByte()
??????? setCalendar()
??????? setCharacter()
??????? setDate()
??????? setDouble()
??????? setText()
??????? setTime()
??????? setTimestamp()
??????? setEntity()//把参数与一个持久化类的事例绑定lsit result = session.createQuery("from order o where o.customer =??????????? :customer").setEntity("customer" , customer).list ;
??????? setParameter()//绑定任意类型的参数
??????? setProperties()//把命名参数与一个对象的属性值绑定 Query query = session.createQuery("from customer c where c.name =:???? name " + "and c.age =:age" );
??????? Query.setProperties(customer);
过滤查询结果中的重复元素
???? 使用Set集合来去除重复元素；或是使用distinct元素
???? Iterator iterator = session.createQuery("select distinct c.name from customer ").list().iterator();
???? while(iterator.hasnext()){
?????????? String name = (String) it.next() ;
???? }
///////////使用聚集函数
count(); 记录的条数
min();?? 求最小值
max();?? 求最大值
avg();?? 求平均值
sum();?? 求和
1'查询customer中的所有记录条数
?? integer i = (Integer) session.createQuery("select count(*) from customer").uniqueResult();
2'查询customer中的所有客户的平均年龄
?? integer i = (Integer) session.createQuery("select avg(c.age) from customer c ").uniqueResult();
3'查询customer中的客户年龄的最大值、最小值
?? object [] i = (Integer) session.createQuery("select max(c.age),min(c.age) from customer c ").uniqueResult();
?? Integer Maxage = (Integer) i [0];
?? Integer Minage = (Integer) i [1];
4'统计customer中的客户的名称数目，忽略重复的姓名
?? Integer cout = (Integer) session.createQuery("select count(distinct c.name) from customer c").uniqueResult();
////////////使用分组查询
1'按姓名分组，统计customer中的相同姓名的记录数目
?? Iterator iterator = (Integer) session.createQuery("select c.name ,count(c) from customer c group by c.name").list.iterator();
?? while(iterator.hasnext()){
???????? object[] p = (objcet[])iterator.next();
???????? String name = p[0];
???????? Integer cout = p[1];
?? }
2'按客户分组，统计每个客户的订单数量
?? Iterator iterator = session.crateQuery("select c.id ,c.name , count(o) from customer c join c.order o group by c.id ").list().iterator;
?? while(iterator.hasnext()){
???????? object[] p = (objcet[])iterator.next();
???????? Integer id = p[0]
???????? String name = p[1];
???????? Integer cout = p[2];
?? }
3'统计每个客户的订单总价
?? Iterator iterator = session.crateQuery("select c.id ,c.name,sum(o.price) from customer c join c.order o group by c.id").list.iterator();
?? while(iterator.hasnext()){
???????? object[] p = (objcet[])iterator.next();
???????? Integer id = p[0]
???????? String name = p[1];