Hibernate 的HQL,QBC 查询语言

1.HQL:(Hibernate Query Language) 是面向对象的查询语言 

1.实体查询 

public void testQueryAllDept(){
String hql="from Employee";
       //hql="from com.sh.Entity";
Query query=session.createQuery(hql);

List list= query.list();

//...
}

2.有条件的 实体查询 

public void testQueryAllDept(){
String hql="from Deptas model where mode.deptName='人事部' ";
       //hql="from com.sh.Entity";
Query query=session.createQuery(hql);

List list= query.list();

//...
}
public void testQueryAllDept(){
String hql="from Deptas model where mode.deptName like '%部%' ";
       //hql="from com.sh.Entity";
Query query=session.createQuery(hql);

List list= query.list();

//...
}

 public void testQueryDeptByGt(){

 String hql="from Dept model where model.createDate> '2012-03-10'";
 Query query=session.createQuery(hql);
 List list= query.list();
 }

3.HQL 中的各种运算符 

运算符类型	HQL运算符	含义
比较运算	=	等于
	<>	不等于
	>	大于
	>=	大于等于
	<=	小于等于
	<	小于
	is null	为空
	is not null	不为空
范围运算	in	等于列表中的某一值
	not in	不等于列表中的任意一个值
	between  p1 and p2	大于等于值1  且 小于等于值2
	not between p1 and p2	小于值1 或者 大于 值2
字符串模式匹配	like	字符串模式匹配
逻辑运算	and	与
	or	或
	not	非

3.更新 删除 

public void testModifyDate(){
        Transaction tr=session.beginTransaction();
        Dept detp=(Dept)session.get(Detp.class,new Integer(6));
        detp.seteCreateDate("2000-03-10");
        tr.commit();

    }

// delete  删除
public void testDelDeptByHql(){
        Transaction tr=session.beginTransaction();
        String hql="delete Dept as model where model.deptId=6";
        Query query=session.createQuery(hql);
        query.executeUpdate();
        tr.commit();
    }

4.属性查询 

public void testQueryDeptName(){
    String hql="select model.deptName from Dept as model";
    Query query=session.createQuery(hql);
    List deptNameList=query.list();
    //...
}
       public void testQueryDeptName(){
    String hql="select model.deptName,model.createDate from Dept as model";
    Query query=session.createQuery(hql);
    List prsList=query.list();
               for(){
               }
    //...
}

   //采用对象进行 保存 查询的字段(要添加 对应字段的构造方法)
    public void testQueryDeptName(){
    String hql="select new Dapt(model.deptName,model.createDate) from Dept as model";
    Query query=session.createQuery(hql);
    List deptList=query.list();
               for(Dept d:deptList){

                  d.setDeptName("test");
                  session.saveOrUpdate(dept);
               }
    //...
}


   //如果采用对象 保存上面查询出来的对象  如果对其进行更新的操作 是不会成功的

public void testSaveDept(){
    Transction  tr=session.beginTransactino();
    String hql="select new Dept(model.deptName,model.createDate) from Dept as model";
    Query query=session.createQuery();
    List deptList=query.list();
    for(Dept dept:deptList){
        System.out.println(dept.deptName);
        dept.setDetpName("test");
        session.saveOrUpdate(dept);
    }
    tr.commit();
      // 最后 根本就没有更新 而是 在数据库中 插入 新的记录
}

5.使用函数 

public void testQuyeryFunction(){
        String hql="select count(*),min(model.createDate) from Dept as model";
        Query query=session.createQuery(hql);
        List paramsList=query.list();
        for(){

        }
        //...
    }

6.分组 与 排序 

//排序
public void testQueryOrderBy(){
        String hql="from Dept as mode order by   model.createDate,model.deptName desc";
        Query query=session.createQuery();
        List deptList=query.list();
        for(){}
        //

    }

//分组 并且 使用  having 筛选
public void testQueryGroupBy(){
        String hql="select count(model),model.deptName from Dept as model group by model.deptName having count(model)>1";
        Query query=session.createQuery();
        List list=query.list();
        //...
    }

7.查询单个对象 

public void testQueryUn(){
        String hql="select model.deptName from Dept as model where model.deptId=2";
        Query query=session.createQuery(hql);
        query.setMaxResults(1);
        String deptName=(String)query.uniqueResult();
        System.out.println(deptNamae);
    }

8.绑定参数 
释义:Hibernate中也采用了preparedStatement作为底层数据库的的访问方式,与之对应的SQL语句 可以重用preparedStatement对象, 首先会预编译,然后缓存起来,提高性能. 

1.使用 ":"加参数名 绑定参数 

public void  testQueryByParamsName(){
           //使用  ":参数名" 来传递参数
    String hql="from Dept as model where
odel.deptName=:deptName and model.createDate=:createDate";

    Query query=session.createQuery(hql);
    query.setString("deptName","test");
    query.setString("ceateDate","2000-02-10");
    List deptList=query.list();
    for(){}

    //...

}

2.使用 "?" 按照位置来绑定参数 

public void testQueryByParamsID(){
    String hql="from Dept as model where model.deptName=? and model.createDate=?";
    Query query=session.createQuery(hql);
    query.setString(0,"test");
    query.setString(1,"2000-02-02");
    List list=query.list();
    for(){}
    //..
}

3.采用setEntity() 将参数和一个持久化对象进行绑定 

public void testQueryByDept(){
        Dept dept=(Dept)Session.get(Dept.clas,new Integer(2));
        String hql="select Employee  as model where model.dept=?"
        Query query=session.createQuery(hql);
        query.setEntity(0,dept);
        List empList=query.list();
        for(){}
        //..


    }

4.setParameter() 用于绑定任意类型的参数 

public void testQueryBySetParams(){
        String hql="from Dept as model where model.deptName=?";
        Query query=session.createQuery(hql);
        query.setParameter(0,"test");
        List deptList=query.list();
        for(){}
        //..
    }

5.setProperties() 将一个参数名 于一个对象的属性值绑定 

public void testQueryBySetPro(){
        Dept deptNew=new  Dept();
        deptNew.setDeptName("test");

        String hql="from Dept as model where model.deptName=:deptName";
        Query query=session.createQuery();
        query.setProperties(deptNew);
        List deptList=query.list();
        for(){

        }
        //..

    }

10. 联合查询 
inner join 

public void testQueryInnerJoin(){
        String hql="from Dept as model inner join model1.employees as model2";
        Query query=session.createQuery(hql);
        List objList=query.list();
        for(Object[] obj:objList){
            Dept dept=(Dept)obj[0];
            Employee emp=(Employee)obj[1];
            System.out.println("xxxx");
        }
    }

left join 

public void testQueryLeftJoin(){
        String hql="from Dept as model left join model1.employees as model2";
        Query query=session.createQuery(hql);
        List objList=query.list();
        for(Object[] obj:objList){
            Dept dept=(Dept)obj[0];
            Employee emp=(Employee)obj[1]; //有可能为空 所以需要判断
            if(mep!=null){
                System.out.println("xxxx");
            }else{
                System.out.println(null);
            }
            System.out.println(dept.getDeptName());
        }
    }

right join 

public void testQueryRightJoin(){
    String hql="from Dept as model right join model1.employees as model2";
    Query query=session.createQuery(hql);
    List objList=query.list();
    for(Object[] obj:objList){
        Dept dept=(Dept)obj[0];
        Employee emp=(Employee)obj[1]; //有可能为空 所以需要判断
        if(dept!=null){
            System.out.println(dept.getDeptName());
        }else{
            System.out.println(null);
        }
        System.out.println("dd"+emp.getEmployeeName());
    }
}

11.子查询 

public void testQueryChild(){
    String hql="from Dept as model where (select count(*) from model.employee) >2";
    Query query=session.createQuery(hql);
    List objList=query.list();
    for(){}
    //..
}

12 Criteria 查询 
释义:通过面向对象的设计将数据查询条件封装在一个对象 

//无条件
public void testQueryDept(){
        Criteria criteria=session.createCriteria(Dept.class);
        List deptList=criteria.list();
        for(){}
        //..
    }

//添加条件
public void testQueryDeptByName(){
        Criteria criteria=session.createCriteria(Dept.class);
        criteria.add(Expression.eq("deptName", "人事部"));
        List deptList=criteria.list();
        for(){}
        //..
    }

SQL语法查询机制 

方法	描述
Expression.eq	对应sql中的field =value
Expression.gt	对应sql中的field>value
Expression.ge	对应sql中的field>=value
Expression.lt	对应sql中的field
Expression.le	对应sql中的field<=value
Expression.between	对应sql中的between
Expression.like	对应 like
Expression.in	对应 in
Expression.eqProperty	用于比较两个属性之间的值,对应的Sql条件中field=field
Expression.gtProperty	用于比较两个属性之间的值,对Sqlfiled>field
Expression.geProperty	用于比较两个属性之间的值,对应sql field>=field
Expression.ltProperty	用于比较两个属性之间的值,对应field
Expression.leProperty	用于比较 两个属性之间的值,对应field<=field

Hibernate3中采用Restrictions类代替Expression 

public void  testQueryDeptByNameRe(){
        Criteria  criteria=session.createCriteria(Dept.class);
        criteria.add(Restrictions.eq("deptName", "人事部"));
        List deptList=criteria.list();
        for(){}
        //..

    }

Criteria中限定返回的行数 

public void testQueryDept(){
        Criteria criteria=session.createCriteria(Dept.class);
        criteria.setFirstResult(2);
        criteria.setMaxResults(2);
        List deptList=criteria.list();
        for(){}
        //..
    }

Criteria排序 

 
       
       public void testQueryDept(){   
               Criteria criteria=session.createCriteria(Dept.class);   
               criteria.addOrder(Order.asc("createDate"));   
               List deptList=criteria.list();   
               for(){}   
               //..   
           }
public void testQueryDept(){
        Criteria criteria=session.createCriteria(Dept.class);
        criteria.addOrder(Order.asc("createDate"));
        List deptList=criteria.list();
        for(){}
        //..
    }

转载于:https://www.cnblogs.com/OldZhao/p/5134979.html