mybatis 一对多查询

Mappe文件

<resultMap type="BwProject" id="BwProjectResult">
        <id property="id" column="id" />
        <result property="projectCode" column="PROJECT_CODE" />
        <result property="projectName" column="PROJECT_NAME" />
        <result property="status" column="STATUS" />
        <result property="voltage" column="VOLTAGE" />
        <result property="constructionUnit" column="CONSTRUCTION_UNIT" />
        <result property="contractAmount" column="CONTRACT_AMOUNT" />
        <result property="researchReplyTime" column="RESEARCH_REPLY_TIME" />
        <result property="desiginReplyTime" column="DESIGIN_REPLY_TIME" />
        <result property="budgetReplyTime" column="BUDGET_REPLY_TIME" />
        <result property="materialBiddTime" column="MATERIAL_BIDD_TIME" />
        <result property="compleOperateTime" column="COMPLE_OPERATE_TIME" />
        <result property="createPeople" column="CREATE_PEOPLE" />
        <result property="createTime" column="CREATE_TIME" />
        <result property="updatePeople" column="UPDATE_PEOPLE" />
        <result property="updateTime" column="UPDATE_TIME" />
        <collection property="children" ofType="com.booway.project.domain.BwEngineering" column="pid">
            <id property="id" column="eid" />
            <result property="pid" column="pid" />
            <result property="engineerCode" column="ENGINEER_CODE" />
            <result property="engineerName" column="ENGINEER_NAME" />
        </collection>
    </resultMap>

    <select id="selectLyPro" parameterType="BwProject"
        resultMap="BwProjectResult">
        select a.*,b.ENGINEER_CODE,b.id as eid,b.pid from bw_project a LEFT JOIN bw_engineering b on a.id=b.pid
    </select>

实体类

/**
     * 主键
     */
    @TableId(value = "ID", type = IdType.AUTO)
    private Long id;
    /**
     * 项目编码
     */
    @TableField(value = "PROJECT_CODE")
    private String projectCode;
    /**
     * 项目名称
     */
    @TableField(value = "PROJECT_NAME")
    private String projectName;
    /**
     * 状态
     */
    @TableField(value = "STATUS")
    private String status;
    /**
     * 电压表
     */
    @TableField(value = "VOLTAGE")
    private String voltage;
    /**
     * 建管单位
     */
    @TableField(value = "CONSTRUCTION_UNIT")
    private String constructionUnit;
    /**
     * 合同款
     */
    @TableField(value = "CONTRACT_AMOUNT")
    private BigDecimal contractAmount;
    /**
     * 可研批复时间
     */
    @TableField(value = "RESEARCH_REPLY_TIME")
    private Date researchReplyTime;
    /**
     * 初设批复时间
     */
    @TableField(value = "DESIGIN_REPLY_TIME")
    private Date desiginReplyTime;
    /**
     * 施工图预算批复时间
     */
    @TableField(value = "BUDGET_REPLY_TIME")
    private Date budgetReplyTime;
    /**
     * 物资招标时间
     */
    @TableField(value = "MATERIAL_BIDD_TIME")
    private Date materialBiddTime;
    /**
     * 竣工投产时间
     */
    @TableField(value = "COMPLE_OPERATE_TIME")
    private Date compleOperateTime;
    /**
     * 创建者
     */
    @TableField(value = "CREATE_PEOPLE")
    private String createPeople;
    /**
     * 创建时间
     */
    @TableField(value = "CREATE_TIME")
    private Timestamp createTime;
    /**
     * 更新者
     */
    @TableField(value = "UPDATE_PEOPLE")
    private String updatePeople;
    /**
     * 更新时间
     */
    @TableField(value = "UPDATE_TIME")
    private Timestamp updateTime;
    /**
     * 虚拟主键
     */
    @TableField(exist = false)
    private String mxVirtualId;
    // 关联工程表
    private List<BwEngineering> children;

 

这里会有个问题  因为bw_project 有字段id  bw_engineering也有字段id

查询的时候 一个bw_project 对应的是多个  bw_engineering 但是只会显示一个  bw_engineering 

那是因为当两个表有相同的字段的时候必须使用别名  这里我把  bw_engineering表的 id 改为了 eid  

此时查询出来的结果就是对的