SSM框架day02-MyBatis——052——关联查询-many2many-多表单独查询

（1）定义中间类

（2）映射文件

<mapper namespace="com.abc.dao.IStudentDao">

    <!-- 多表单独查询 -->

    <select id="selectCourseById" resultType="Course">

        select cid,cname from course where cid=#{jjj}

    </select>

    <resultMap type="Middle" id="middleMap">

        <id column="id" property="id"/>

        <association property="course"

                     javaType="Course"

                     select="selectCourseById"

                     column="courseId"/>

    </resultMap>

    <select id="selectMiddleByStudent" resultMap="middleMap">

        select id,courseId from middle where studentId=#{ooo}

    </select>

    <resultMap type="Student" id="studentMap">

        <id column="sid" property="sid" />

        <result column="sname" property="sname" />

        <collection property="courses"

                    ofType="Course"

                    select="selectMiddleByStudent"

                    column="sid"/>

    </resultMap>

    <select id="selectStudentById" resultMap="studentMap">

        select sid,sname from student where sid=#{xxx}

    </select>

</mapper>

（3）多表复杂查询