一、实体类实现增删改查

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1.1、增 > insert

①抽象接口

Integer addUserInfo(User user);

②xml

• 这里要注意关键字的书写方式
• like要用括号来包起来，防止跟关键字引起冲突！

    <insert id="addUserInfo" parameterType="com.dbright.pojo.User">
        insert into user(name,age,`like`)values(#{name},#{age},#{like} )
    </insert>

③测试类

• session.commit(); 这个是提交事务！必须得写，不然语句不会生效！

    @Test
    public void addUserInfo() {
        SqlSession session = MybatisUtils.getSession();
        UserMapper mapper = session.getMapper(UserMapper.class);

        //造数据
        User user = new User();
        user.setName("面条");
        user.setAge(22);
        user.setLike("王者荣耀");
        Integer statusNum = mapper.addUserInfo(user);
        System.out.println(statusNum);

        session.commit();//提交事务
        session.close();
    }

④执行结果

image.png image.png

1.2、删 > delete

①抽象接口

Integer deleteUserInfo(int id);

②xml

    <delete id="deleteUserInfo" parameterType="int">
        delete from user where id = #{id}
    </delete>

③测试类

• 删除也需要提交事务才会生效！

    @Test
    public void deleteUserInfo() {
        SqlSession session = MybatisUtils.getSession();
        UserMapper mapper = session.getMapper(UserMapper.class);
        Integer statusNum = mapper.deleteUserInfo(26);
        System.out.println(statusNum);

        session.commit();//提交事务
        session.close();
    }

④执行结果

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1.3、改 > update

①抽象接口

Integer updateUserInfo(User user);

②xml

    <update id="updateUserInfo" parameterType="com.dbright.pojo.User">
        update user set name = #{name},age = #{age},`like` = #{like} where id = #{id}
    </update>

③测试类

    @Test
    public void updateUserInfo() {
        SqlSession session = MybatisUtils.getSession();
        UserMapper mapper = session.getMapper(UserMapper.class);

        //造数据
        User user = new User();
        user.setId(30);
        user.setName("丁大大");
        user.setAge(23);
        user.setLike("钓鱼");
        Integer statusNum = mapper.updateUserInfo(user);
        System.out.println(statusNum);

        session.commit();//提交事务
        session.close();
    }

④执行结果

• 原先：

image.png

• 执行后：

image.png

1.4、查 > select

①抽象接口

    List<User> getUserInfo();

    User getUserInfoById(int id);

    User getUserInfoByIF(@Param("name") String name , @Param("age") Integer age);

②xml

    <select id="getUserInfo" resultType="com.dbright.pojo.User">
        select * from user
    </select>

    <select id="getUserInfoById" resultType="com.dbright.pojo.User">
        select
               *
        from
             user
        where
            id = #{id}
    </select>

    <select id="getUserInfoByIF" resultType="com.dbright.pojo.User">
        select
               *
        from
             `user`
        where
            `name` = #{name}
        and
            age = #{age}
    </select>

③测试类

    @Test
   public void selectUser() {
       SqlSession session = MybatisUtils.getSession();
       UserMapper mapper = session.getMapper(UserMapper.class);
       List<User> users = mapper.getUserInfo();

       for (User map: users){
           System.out.println(map);
      }
       session.close();
  }
  @Test
  public void getUserInfoById() {
      SqlSession session = MybatisUtils.getSession();
      UserMapper mapper = session.getMapper(UserMapper.class);

      User userInfo = mapper.getUserInfoById(30);
      System.out.println(userInfo);

      session.close();
  }

    @Test
    public void getUserInfoByIF() {
        SqlSession session = MybatisUtils.getSession();
        UserMapper mapper = session.getMapper(UserMapper.class);

        User userInfo = mapper.getUserInfoByIF("丁大大",23);
        System.out.println(userInfo);

        session.close();
    }

④执行结果

• 数据如下：

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• 查询表里所有信息

image.png

• 待条件查询

image.png

• 多条件查询

image.png

二、Map实现增删改查

• 这里不举太多例子了，因为mapper会自动将map中的值根据key对应起来
• 十分方便，在实际工作中，使用Map查询居多
• 前提是前后端联调使用的是PostMan或者Yapi等联调工具
• 如果使用swaager联调，必须使用实体类来进行开发
• 例子：

①接口类

Integer addUserInfo(Map<String,Object> map);

②xml

    <insert id="addUserInfo" parameterType="map">
        insert into user(name,age,`like`)values(#{name},#{age},#{like} )
    </insert>

③测试类

    @Test
    public void addUserInfo() {
        SqlSession session = MybatisUtils.getSession();
        UserMapper mapper = session.getMapper(UserMapper.class);

        //造数据
        Map<String,Object> map = new HashMap<>();
        map.put("name","面条");
        map.put("age","50");
        map.put("like","王者荣耀");
        Integer statusNum = mapper.addUserInfo(map);
        System.out.println(statusNum);

        session.commit();//提交事务
        session.close();
    }

④执行结果

image.png

作者：大鱼丶
原文链接：https://juejin.cn/post/6982743087143452708