Hibernate 中的 DetachedCriteria查询(所有使用到的类属性必须在映射文件中存在)

DetachedCriteria对象为hibernate的离线查询对象(即该对象不是由session创建[由forClass或者forEntityName来创建]，查询的动态sql语句在web层即可以生成[即可以脱离session来动态构建sql语句，进行查询])
查找哪一个类：


  DetachedCriteria criteria = DetachedCriteria.forClass(Project.class);


判断类属性(表中列，以后直接用列表示)是否等于某个值：


DetachedCriteria.add(Restrictions.eq("user.id", userId));


or查询条件


        Criterion leader = Restrictions.eq("leader.id", userId);
        Criterion member = Restrictions.eq("members.member.id", userId);
        LogicalExpression orExp1 = Restrictions.or(leader, member);
        criteria.add(orExp1);
like查询条件


Criterion fullName = Restrictions.like("fullName", findKey);
Criterion shortName = Restrictions.like("shortName", findKey);
Criterion leaderName = Restrictions.like("key", findKey);
LogicalExpression orExp = Restrictions.or( Restrictions.or(fullName, shortName), leaderName);
criteria.add(orExp);


5、查询数据一共有多少条


DetachedCriteria criteria = this.createFindProjectsCriteria(findKey, userId, scope) ;
criteria.setProjection(Projections.rowCount());
List results = getHibernateTemplate().findByCriteria(criteria);
int count = ((Integer) results.get(0)).intValue();
return count;
查询不重复的数据条数(其它同5)
 criteria.setProjection(Projections.countDistinct("key"));根据主键key来查


动态关联查询


     List cats = sess.createCriteria(Cat.class)
    .add( Restrictions.like("name", "Fritz%") )
    .setFetchMode("mate", FetchMode.EAGER)
    .setFetchMode("kittens", FetchMode.EAGER)
.list();

添加按列排序：


criteria.addOrder(Order.asc(类的属性));


去掉重复项  ：


(1)criteria.setResultTransformer(DetachedCriteria.DISTINCT_ROOT_ENTITY);
(2)detachedCriteria.setProjection(Projections.distinct(Projections.property(str)));


detachedCriteria.setProjection(Projections.groupProperty(str));
使用自定义的sql语言查询
criteria.add(Restrictions.sqlRestriction("  project_Id="+projectId+" connect by prior id= prev_ver "));
使用自定义的sql返回实体类的集合
criteria.add(Restrictions.sqlRestriction("  project_Id="+projectId+" connect by prior id= prev_ver ")).addxxx();
Query query =session.createSQLQuery(sql).addEntity(Project.class);
query.setString("active", "Y");
query.setLong("leaderId", userId); 
条件拼装完成后，边可以进行查询了 ：
getHibernateTemplate().findByCriteria