8.通用Mapper常见接口方法

　１.select方法　

@Test
    /**
     * 根据属性值进行查询,以等号方式查询
     * <p>Title: testSelect</p>
     * <p>Description: select * from user where id=110</p>
     * @throws Exception
     */
    public void testSelect() throws Exception {
        /*
            查询id=100的数据
            User u = new User();
            u.setId(110);
            userMapper.select(u);
        */
        // user表中所有的数据信息
        List<User> list = userMapper.select(null);
        System.out.println(list);
    }

 

2.按主键查询

    @Test
    /**
     * 按表中主键查询数据
     * <p>Title: testselectByPrimaryKey</p>
     * <p>Description: </p>
     * @throws Exception
     */
    public void testSelectByPrimaryKey() throws Exception {
        User u = userMapper.selectByPrimaryKey(6);
        System.out.println(u);
    }

3.查询表中所有的数据

    /**
     * 查询user表中所有数据
     * <p>Title: testSelectAll</p>
     * <p>Description: </p>
     * @throws Exception
     */
    @Test
    public void testSelectAll() throws Exception {
        List<User> list = userMapper.selectAll();
        System.out.println(list);
    }

4.查询单条记录

    /**
     * 根据条件查询单条数据
     * <p>Title: testSelectOne</p>
     * <p>Description: </p>
     * @throws Exception
     */
    @Test
    public void testSelectOne() throws Exception {
        User u=new User();
        u.setId(2);
        User user = userMapper.selectOne(u);
        System.out.println(user);
    }

5.根据属性值查询总记录数

    @Test
    /**
     * 根据属性值查询数据总数
     * <p>Title: testSelectCount</p>
     * <p>Description: </p>
     * @throws Exception
     */
    public void testSelectCount() throws Exception {
        User u=new User();
        u.setFlag(1);//查询正常用户信息  1=正常 0=软删除
        int count = userMapper.selectCount(u);
        System.out.println("共有用户:"+count);
    }

6.保存数据

    @Test
    /**
     * 保存用户
     * <p>Title: testInsert</p>
     * <p>Description: </p>
     */
    public void testInsert()
    {
        User u=new User();
        u.setName("kkkkk");
        u.setAge(30);
        u.setFlag(1);
        userMapper.insert(u);  // insert()如果属性null为空 也会保存
        System.out.println(u);
        
        userMapper.insertSelective(u);//如果属性null则不会保存
        
    }

修改

updateByPrimaryKey

updateByPrimaryKeySelective

 

删除

delete

deleteByPrimaryKey