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Mybatis关联查询结果集对象嵌套的具体使用

在查询时经常出现一对多”的关系,所有会出现嵌套对象的情况，本文主要介绍了Mybatis关联查询结果集对象嵌套的具体使用，文中通过示例代码介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们可以参考一下

在查询时经常出现一对多”的关系,所有会出现嵌套对象的情况，Mybatis在resultMap提供了collection标签，本文适合有一定Mybatis基础的读者查阅

数据模型WeixinActivity2018User.java

public class WeixinActivity2018User  implements Serializable{

    /** serialVersionUID*/

    private static final long serialVersionUID = -2740162776768956231L;

    private int id;

    private String nickname;  //昵称

    private String headurl;   //头像

    private String openid;    //微信用户OpenId

    private String unionid;

    private String phone;     //用户手机号

    private int count;        //积攒数

    private String createtime;//创建时间

    private String uptime;    //更新时间

    private List<WeixinActivity2018UserAssist> activity2018UserAssists;//点赞用户信息

数据模型WeixinActivity2018UserAssist.java

public class WeixinActivity2018UserAssist  implements Serializable{

    /** serialVersionUID*/

    private static final long serialVersionUID = -2740162776768956232L;

    private int aid;

    private int uid;

    private String nickname;

    private String headurl;

    private String openid;

    private String unionid;

    private String createtime;

WeixinActivity2018UserMapper.xml

  <resultMap id="BaseResultMap" type="com.lh.wx.model.WeixinActivity2018User">

    <id column="id" jdbcType="INTEGER" property="id" />

    <result column="openid" jdbcType="VARCHAR" property="openid" />

    <result column="unionid" jdbcType="VARCHAR" property="unionid" />

    <result column="phone" jdbcType="VARCHAR" property="phone" />

    <result column="nickname" jdbcType="VARCHAR" property="nickname" />

    <result column="headurl" jdbcType="VARCHAR" property="headurl" />

    <result column="count" jdbcType="INTEGER" property="count" />

    <result column="createtime" jdbcType="DATE" property="createtime" />

    <result column="uptime" jdbcType="DATE" property="uptime" />

    <collection  property="activity2018UserAssists"  ofType="com.lh.wx.model.WeixinActivity2018UserAssist">

            <id property="aid" column="aid" />

             <result column="uid" jdbcType="INTEGER" property="uid" />

            <result column="aopenid" jdbcType="VARCHAR" property="openid" />

            <result column="aunionid" jdbcType="VARCHAR" property="unionid" />

            <result column="anickname" jdbcType="VARCHAR" property="nickname" />

            <result column="aheadurl" jdbcType="VARCHAR" property="headurl" />

            <result column="acreatetime" jdbcType="DATE" property="createtime" />

    </collection>

  </resultMap>

  <sql id="Base_Column_List">

    openid,unionid,phone,nickname,headurl,count,createtime,uptime

  </sql>

  <insert id="insertActivity2018User"  useGeneratedKeys="true" keyProperty="id" parameterType="com.lh.wx.model.WeixinActivity2018User" >

    insert into t_weixin_activity_2018_user (openid,unionid,phone,nickname,headurl,createtime,uptime)

    values (

        #{openid,jdbcType=VARCHAR},#{unionid,jdbcType=VARCHAR},#{phone,jdbcType=VARCHAR}, #{nickname,jdbcType=VARCHAR}, #{headurl,jdbcType=VARCHAR},now(),now()

)

  </insert>

    <select id="selectTalCount" resultType="java.lang.Integer"  parameterType="java.util.Map">

        SELECT  count(twau.id)

        from  t_weixin_activity_2018_user twau

        <if test="openid != '' and openid != null">

            and twau.openid = #{openid}

        </if>

        <if test="id != 0 and id != null">

            and twau.id = #{id}

        </if>

        <if test="phone != '' and phone != null">

            and twau.phone = #{phone}

        </if>

    </select>

    <select id="queryActivity2018User" parameterType="java.util.Map" resultMap="BaseResultMap" >

        SELECT 

         twau.id,twau.openid, twau.unionid, twau.phone, twau.nickname, twau.headurl, twau.count,date_format( twau.createtime, '%Y-%m-%d %H:%m:%s') as createtime,date_format( twau.uptime, '%Y-%m-%d %H:%m:%s') as uptime

        ,twaua.aid,twaua.uid,twaua.openid as aopenid,twaua.unionid as aunionid,twaua.nickname as anickname,twaua.headurl as aheadurl,date_format(twaua.createtime, '%Y-%m-%d %H:%m:%s') as acreatetime ,

        twaua.phone as aphone

        from  t_weixin_activity_2018_user twau LEFT  JOIN t_weixin_activity_2018_user_assist twaua on twau.id=twaua.uid  where 1=1

        <if test="openid != '' and openid != null">

            and twau.openid = #{openid}

        </if>

        <if test="id != 0 and id != null">

            and twau.id = #{id}

        </if>

        <if test="phone != '' and phone != null">

            and twau.phone = #{phone}

        </if>

        <if test="start != '' and start != null  and start != 0">

            order by tlb.createtime desc limit ${start}, ${number}

        </if>

  </select>

到此这篇关于Mybatis关联查询结果集对象嵌套的具体使用的文章就介绍到这了

原文链接：https://blog.csdn.net/BuFanQi_Info/article/details/78973671