spring-boot-realworld-example-app/src/main/resources/mapper/ArticleReadService.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="io.spring.application.article.ArticleReadService">
    <sql id="profileColumns">
        U.id userId,
        U.username userUsername,
        U.bio userBio,
        U.image userImage
    </sql>
    <sql id="selectArticleData">
        select
        A.id articleId,
        A.slug articleSlug,
        A.title articleTitle,
        A.description articleDescription,
        A.body articleBody,
        A.created_at articleCreatedAt,
        A.updated_at articleUpdatedAt,
        T.name tagName,
        <include refid="profileColumns"/>
        from
        articles A
        left join article_tags AT on A.id = AT.article_id
        left join tags T on T.id = AT.tag_id
        left join users U on U.id = A.user_id
    </sql>

    <select id="findById" resultMap="articleData">
        <include refid="selectArticleData"/>
        where A.id = #{id}
    </select>
    <select id="findBySlug" resultMap="articleData">
        <include refid="selectArticleData"/>
        where A.slug = #{slug}
    </select>

    <resultMap id="articleData" type="io.spring.application.article.ArticleData">
        <id column="articleId" property="id"/>
        <result column="articleSlug" property="slug"/>
        <result column="articleTitle" property="title"/>
        <result column="articleDescription" property="description"/>
        <result column="articleBody" property="body"/>
        <result column="articleCreatedAt" property="createdAt"/>
        <result column="articleUpdatedAt" property="updatedAt"/>
        <association property="profileData" resultMap="profileData"/>
        <collection property="tagList" javaType="list" ofType="string">
            <result column="tagName"/>
        </collection>
    </resultMap>

    <resultMap id="profileData" type="io.spring.application.profile.ProfileData">
        <id column="userId" property="id"/>
        <result column="userUsername" property="username"/>
        <result column="userBio" property="bio"/>
        <result column="userImage" property="image"/>
    </resultMap>
</mapper>