mybatis增删改查（练习2）

namespace中的包名要和 Dao/mapper 接口的包名一致！

 选择，查询语句;

id : 就是对应的namespace中的方法名；resultType：Sql语句执行的返回值！parameterType ： 参数类型！

maven项目的clean与package

    //insert一个用户
    int addUser(User user);

    
    
    
        insert into mybatis.user (id, name, pwd) values (#{id},#{name},#{pwd});
    

    @Test
    public void addUser(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserDao mapper = sqlSession.getMapper(UserDao.class);
       int res=mapper.addUser( new User(6,"ll","123456"));
        if(res>0){
            System.out.println("插入成功！");
        }
        //提交事务
        sqlSession.commit();
        sqlSession.close();
    }

//修改用户
    int updateUser(User user);

    
        update mybatis.user set name=#{name},pwd=#{pwd}  where id = #{id} ;
    

   @Test
    public void updateUser(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserDao mapper = sqlSession.getMapper(UserDao.class);
        mapper.updateUser(new User(4,"jj","123456"));
        //提交事务
        sqlSession.commit();
        sqlSession.close();
    }

 //删除一个用户
    int deleteUser(int id);

    
        delete from mybatis.user where id=#{id};
    

    @Test
    public  void deleteUser(){
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        UserDao mapper = sqlSession.getMapper(UserDao.class);
        mapper.deleteUser(4);
        sqlSession.commit();
        sqlSession.close();
    }