Mybatis一对多关联查询，返回结果集list中嵌套list实例(collection实现)
<select id="selectListByMercId" resultType="...MercSettlePojo">
<![CDATA[
select
,
t.settle_name as settleName <!-- 注意一定要让别名与pojo中的属性一致 -->
from Settle t
]]>
<where>
merc_id = #{merc_id}
</where>
</select>
<select id="selectMerchantList" parameterType="...MercPojo" resultMap="baseResultMap">
<![CDATA[
select ,m.merc_num,m.merc_name
...
from Merchant m
]]>
<where>
<if test="mercNum != null and mercNum != ''"><![CDATA[and m.merc_num LIKE '%'||#{mercNum}||'%']]></if>
<if test="mercName != null and mercName != ''"><![CDATA[and m.merc_name LIKE '%'||#{mercName}||'%']]></if>
...
</where>
</select>
<resultMap id="baseResultMap" type="...MercPojo">
<result column="id" property="id" />
<result column="merc_num" property="mercNum" />
<result column="merc_name" property="mercName" />
...
<!-- 下面这句很重要：作用就是通过selectListByMercId查出list然后映射到属性mercSettleList中。其中，ofType为list的泛型，column为子select的入参(这里是id)，select为子查询的mapperId-->
<collection property="mercSettleList" ofType="...MercSettlePojo" column="{merc_id=id}" select="selectListByMercId"/>
</resultMap>