Mybatis 一对一、一对多的关联查询

<mapper namespace="com.lcb.mapping.userMapper">
	<!--association 一对一关联查询 -->
	<select id="getClass" parameterType="int" resultMap="ClassesResultMap">
		select * from class c,teacher t where c.teacher_id=t.t_id and c.c_id=#{id}
	</select>
	
	<resultMap type="com.lcb.user.Classes" id="ClassesResultMap">
		<!-- 实体类的字段名和数据表的字段名映射 -->
		<id property="id" column="c_id"/>
		<result property="name" column="c_name"/>
		<association property="teacher" javaType="com.lcb.user.Teacher">
			<id property="id" column="t_id"/>
			<result property="name" column="t_name"/>
		</association>
	</resultMap>
	
	<!--collection 一对多关联查询 -->
	<select id="getClass2" parameterType="int" resultMap="ClassesResultMap2">
		select * from class c,teacher t,student s where c.teacher_id=t.t_id and c.c_id=s.class_id and c.c_id=#{id}
	</select>
	
	<resultMap type="com.lcb.user.Classes" id="ClassesResultMap2">
		<id property="id" column="c_id"/>
		<result property="name" column="c_name"/>
		<association property="teacher"  javaType="com.lcb.user.Teacher">
			<id property="id" column="t_id"/>
			<result property="name" column="t_name"/>
		</association>
		<collection property="student" ofType="com.lcb.user.Student">
			<id property="id" column="s_id"/>
			<result property="name" column="s_name"/>
		</collection>
	</resultMap>
</mapper>