mybatis 配置返回集合collection时只有一条记录

查询语句配置如下：

<select id="selectCustomerList" resultMap="CustomerDtoMap" parameterType="map">
    select * from
    (
        select <include refid="AliasCustomerColumnList"/>
        from customer c
    ) c
    left join display_venue_reserve dvr
    on c.c_customer_id = dvr.customer_id where 1=1
    <if test="customerMgrId != null">
        and c.c_customer_mgr_id = #{customerMgrId}
    </if>
    <if test="status != null">
        and dvr.status = #{status}
    </if>
</select>

resultMap配置如下

<resultMap id="CustomerDtoMap" type="com.al.ec.showroom.dto.customer.CustomerDto" extends="AliasBaseResultMap">
        <collection property="displayVenueReserveDtoList" ofType="com.al.ec.showroom.dto.display.DisplayVenueReserveDto">
            <association property="displayVenueReserve" column="VENUE_RESERVE_ID" javaType="com.al.ec.showroom.model.display.DisplayVenueReserve"
                         resultMap="com.al.ec.showroom.mapper.display.DisplayVenueReserveMapper.BaseResultMap">
            </association>
        </collection>
    </resultMap>

查询出结果如下：

只有一条记录，但是数据库直接执行语句是有多条记录的

经过很多轮的改代码研究，发现是因为

<collection property="displayVenueReserveDtoList" ofType="com.al.ec.showroom.dto.display.DisplayVenueReserveDto">
            <association property="displayVenueReserve" column="VENUE_RESERVE_ID" javaType="com.al.ec.showroom.model.display.DisplayVenueReserve"
                         resultMap="com.al.ec.showroom.mapper.display.DisplayVenueReserveMapper.BaseResultMap">
            </association>
        </collection>

需要在collection节点下添加

<id column="dvr_VENUE_RESERVE_ID" property="venueReserveId" jdbcType="DECIMAL"></id>

更改后代码如下

<resultMap id="CustomerDtoMap" type="com.al.ec.showroom.dto.customer.CustomerDto" extends="AliasBaseResultMap">
        <collection property="displayVenueReserveDtoList" ofType="com.al.ec.showroom.dto.display.DisplayVenueReserveDto">
            <id column="VENUE_RESERVE_ID" property="venueReserveId" jdbcType="DECIMAL"></id>
            <association property="displayVenueReserve" column="VENUE_RESERVE_ID" javaType="com.al.ec.showroom.model.display.DisplayVenueReserve"
                         resultMap="com.al.ec.showroom.mapper.display.DisplayVenueReserveMapper.AliasBaseResultMap">
            </association>
        </collection>
    </resultMap>

一直以为<association>节点有column属性就可以作为主键就可以了。。。。原来是需要在<collection>下添加id子节点

查询结果如下

但是对于这样配置的原理还不是很了解，如果知道的大神希望能在评论里给出回复，感谢

小白，刚接触mybatis不久，记录在此，谨记于心~~