hibernate---session查询

一、hql语句查询（适合多表）

public class MyTest {
    public static void main(String[] args) {

        //查询集合
        Session session = SessionUtil.openSession();
        String hql = "from Emp";
        Query query = session.createQuery(hql);
        @SuppressWarnings("unchecked")
        List<Emp> list = query.list();

        //带条件查询方法1
        String hql2 = "from Emp where empno = ?";
        Query query2 = session.createQuery(hql2);
        query2.setInteger(0, 23);
        Emp emp = (Emp) query2.uniqueResult();

        //带条件查询方法2
        String hql3 = "from Emp where empno = ?";
        Query query3 = session.createQuery(hql3);
        query3.setParameter(0, 23);
        Emp emp2 = (Emp) query3.uniqueResult();

        //带条件查询方法3（命名占位符）
        String hql4 = "from Emp where empno = :xx";
        Query query4 = session.createQuery(hql4);
        query4.setParameter("xx", 23);
        Emp emp3 = (Emp) query4.uniqueResult();

        //分页查询
        String hql5 = "from Emp";
        Query query5 = session.createQuery(hql5);
        query5.setFirstResult(0);
        query5.setMaxResults(10);
        @SuppressWarnings("unchecked")
        List<Emp> list2 = query5.list();

        System.out.println(list);
        System.out.println(emp);
        System.out.println(emp2);
        System.out.println(emp3);
        System.out.println(list2);
    }
}

二、criteria查询（无语句查询，适合单表查询）

　　

private static void run2() {
        //查询集合
        Session session = SessionUtil.openSession();
        Criteria criteria = session.createCriteria(Emp.class);
        List<Emp> list = criteria.list();

        /*
         * 带条件查询方法
         * >                        gt
         * <                        lt
         * ==                        eq
         * !=                        ne
         */
        Criteria criteria2 = session.createCriteria(Emp.class);
        criteria2.add(Restrictions.eq("empno", 23));
        Emp emp = (Emp) criteria2.uniqueResult();

        //分页查询
        Criteria criteria3 = session.createCriteria(Emp.class);
        criteria3.setFirstResult(0);
        criteria3.setMaxResults(2);
        List<Emp> list2 = criteria3.list();

        System.out.println(list);
        System.out.println(emp);
        System.out.println(list2);
    }

三、原生态sql语句查询

private static void run3() {
        //集合查询
        Session session = SessionUtil.openSession();
        String sql = "select * from Emp";
        SQLQuery sqlQuery = session.createSQLQuery(sql);
        sqlQuery.addEntity(Emp.class);
        List<Emp> list = sqlQuery.list();

        //条件查询
        String sql2 = "select * from emp where ename = ?";
        SQLQuery sqlQuery2 = session.createSQLQuery(sql2);
//        sqlQuery2.setParameter(0, "JAMES");
        sqlQuery2.setString(0, "JAMES");
        sqlQuery2.addEntity(Emp.class);
        List<Emp> list2 = sqlQuery2.list();

        //分页查询
        //如果是mysql使用特有的limit
        //如果是oracle使用原生态sql查询

        System.out.println(list);
        System.out.println(list2);
    }