ibatis 实现多表关联，一对多，多对多关系
多张表关联查询，一个产品对应多张图片结果集，同时对应多个联系人实现：
数据结构如下：
整体结构：
@Data
public class FeaturedProducts {
private String characteristicProductId;//特色产品id
private String productsTitle;//产品标题
private String productsDescription;//产品描述
private List<String> productsImage;//产品图片结果集
private List<Contacts> contacts;//特色产品联系人结果集
}
list<Bean>集合结构：
@Data
public class Contacts {
private String contactId;//联系人id
private String name;//联系人姓名
private String phone;//联系人电话
private String qrcode;//联系人二维码
}
最后得到结果集：
[
FeaturedProducts(
characteristicProductId=7b1e2676-067b-11ea-88ec-00ff07e25c4a,
productsTitle=dsd, productsDescription=sdd,
productsImage=[
www.222.png,
https://mmwtest2.oss-cn-hangzhou.aliyuncs.com/image/avatarPic/upload/201712/cardPic1513777343927.jpg,
https://mmwtest2.oss-cn-hangzhou.aliyuncs.com/image/avatarPic/upload/201712/cardPic1513777343927.jpg,
www.444.png, https://mmwtest2.oss-cn-hangzhou.aliyuncs.com/image/avatarPic/upload/201712/cardPic1513777343927.jpg,
https://mmwtest2.oss-cn-hangzhou.aliyuncs.com/image/avatarPic/upload/201712/cardPic1513777343927.jpg
],
contacts=[
Contacts(contactId=2a7f8080-067d-11ea-88ec-00ff07e25c4a, name=mr.wu, phone=13200000000, qrcode=www.qrcode2.com)，
。。。可有多个
]
),
FeaturedProducts(
characteristicProductId=d775aaae-067b-11ea-88ec-00ff07e25c4a,
productsTitle=fdffd,
productsDescription=sdsdad,
productsImage=[
www.555.png,
www.333.png
],
contacts=[
Contacts(contactId=f8976924-067c-11ea-88ec-bbbbbbbbbb, name=mr.zh, phone=13700000000, qrcode=www.qrcode.com)，
。。。可有多个
]
)
]
ibatis xml文件：
1、com.mmw100.enterpriseDetailandProfile.bean.FeaturedProducts为整体结构bean；featuredProductsResultMap对应下面select查询的resultMap；characteristicProductId为分组id
<resultMap class="com.mmw100.enterpriseDetailandProfile.bean.FeaturedProducts" id="featuredProductsResultMap" groupBy="characteristicProductId">
<result column="characteristicProductId" property="characteristicProductId"/>
<result column="productsTitle" property="productsTitle"/>
<result column="productsDescription" property="productsDescription"/>
<result property="productsImage" resultMap="enterpriseDetailSql.imagesResultMa"/>//enterpriseDetailSql为xml命名空间名；imagesResultMa 下面resultMap的id
<result property="contacts" resultMap="enterpriseDetailSql.contactMap"/>//enterpriseDetailSql为xml命名空间名；imagesResultMa 下面resultMap的id
</resultMap>
2、返回List<String>结构 class定义为String
<resultMap id="imagesResultMap" class="java.lang.String">
<result property="url" column="image_url"/>//需要的字段名，如果有多个字段，会默认选第一个
</resultMap>
3、返回List<Bean>结构 class为bean目录 groupBy按照该字段分组
<resultMap id="contactMap" class="com.mmw100.enterpriseDetailandProfile.bean.Contacts" groupBy="contactId">
<result property="contactId" column="contactId"/>
<result property="name" column="name"/>
<result property="phone" column="phone"/>
<result property="qrcode" column="qrcode"/>
</resultMap>
4、select 关联查询 一个商品对应多张图片，多个人员信息
<select id="getFeaturedProducts" parameterClass="com.mmw100.enterpriseDetailandProfile.bean.EnterpriseDetailandProfileInput" resultMap="featuredProductsResultMap">
SELECT
cop.contact_person_id as contactId,cp.characteristic_product_id as characteristicProductId,cp.product_name as productsTitle,pi.product_image_id as imgId,pi.image_url,cp.product_description as productsDescription,cop.`name` as name,cop.telephone AS phone,cop.wechat_qr_code as qrcode
FROM
characteristic_product cp
LEFT JOIN product_image pi ON cp.characteristic_product_id=pi.product_id AND pi.del_flag='0'
LEFT JOIN contact_person cop ON cop.characteristic_product_id=cp.characteristic_product_id AND cop.del_flag='0'
WHERE
cp.ex_enterprise_id=#enterpriseId#
AND cp.del_flag='0'
ORDER BY cp.create_time
</select>
