Mybatis模糊查询之三种定义参数方法和聚合查询、主键回填实现方法

// 根据名字内容模糊查询
    List<User> findByNameLike(String username);

<!-- 使用#定义参数 -->
    <select id="findByNameLike" parameterType="string"             
    resultType="com.mybatisstudy.pojo.User">
        select * from user where username like #{name}
    </select>

// 测试根据名字模糊查询
    @Test
    public void testFindByNameLike(){
        String like = "%l%";
        List<User> list = userMapper.findByNameLike(like);
 
        list.forEach(System.out::println);
    }

<!-- 使用$定义参数 -->
    <select id="findByNameLike" resultType="com.mybatisstudy.pojo.User" parameterType="string">
        select * from user where username like '%${value}%'
    </select>

// 测试根据名字模糊查询
    @Test
    public void testFindByNameLike(){
        String like = "l";
        List<User> list = userMapper.findByNameLike(like);
 
        list.forEach(System.out::println);
    }

<!-- 使用<bind>标签定义参数 -->
    <select id="findByNameLike" parameterType="String" resultType="com.mybatisstudy.pojo.User">
        <bind name="likeName" value="'%' + username + '%'"/>
        select * from user where username like #{likeName}
    </select>

// 查询用户总数
    int findCount();

<!-- 聚合查询 -->
    <select id="findCount" resultType="int">
        select count(id) from user
    </select>

// 测试聚合查询方法
    @Test
    public void testFindCount(){
        System.out.println(userMapper.findCount());
    }

// 主键回填-新增用户
    void add2(User user);

<!-- 主键回填 -->
    <insert id="add2" parameterType="com.mybatisstudy.pojo.User">
        <!-- keyProperty:主键属性名，keyColumn:主键列名，resultType:主键类型，order:执行时机 -->
        <selectKey keyProperty="id" keyColumn="id" resultType="int" order="AFTER">
            select last_insert_id();
        </selectKey>
        insert into user(username,sex,address)
        values (#{username},#{sex},#{address})
    </insert>

// 测试主键回填功能
    @Test
    public void testAdd2(){
        User user = new User("Lions","man","Beijing");
        userMapper.add2(user);
 
        session.commit();
        System.out.println(user.getId());
    }