ibatis 一对多 解决方案

时间:2021-04-24 11:55:52

sqlMap文件中的resultMap:

      <resultMap id="productAndPackageResult" class="productAndPackage" >
          <result column="ID" property="id" jdbcType="DECIMAL" />
        <result column="NAME" property="name" jdbcType="VARCHAR" />
        <result column="DISCTRIPTION" property="disctription" jdbcType="VARCHAR" />
        <result column="DURATION" property="duration" jdbcType="DECIMAL" />
        <result column="STATUS" property="status" jdbcType="DECIMAL" />
        <result column="AD_COUNT" property="adCount" jdbcType="DECIMAL" />
        <result column="BEGIN_TIME" property="beginTime" jdbcType="DATE" />
        <result column="END_TIME" property="endTime" jdbcType="DATE" />
        <result column="MARKET_PRICE" property="marketPrice" jdbcType="DECIMAL" />
        <result column="PRICE" property="price" jdbcType="DECIMAL" />
        <result column="RELEASE_TEL_NUM" property="releaseTelNum" jdbcType="DECIMAL" />
        <result column="RELEVANCE_TEL_NUM" property="relevanceTelNum" jdbcType="DECIMAL" />
         <result property="productPackageList" column="{productId=ID,areaId=areaId,status=status}"
         select="ProductPackageSQL.getByProductId"/> 
      </resultMap>

注意productPackageList字段是,利用了select="ProductPackageSQL.getByProductId"来实现的。

getByProductId的select是这样的:

 

    <select id="getByProductId" resultMap="productPackageResult" parameterClass="java.util.HashMap">
        select * from TB_PRODUCT_PACKAGE where
            PRODUCT_ID = #productId#
             <isNotNull property="areaId" prepend="and">
                AREA_ID = #areaId#
            </isNotNull>
            <isNotNull property="status" prepend="and">
                STATUS = #status#
            </isNotNull>
        
    </select>

 

productAndPackageResult 用到的地方:
    <select id="getList" resultMap="productAndPackageResult" parameterClass="java.util.Map">
        select ID,NAME,DISCTRIPTION,DURATION,STATUS,PRICE,AD_COUNT,BEGIN_TIME,END_TIME,
        MARKET_PRICE,PRICE,RELEASE_TEL_NUM,RELEVANCE_TEL_NUM ,#areaId# as areaId,#status# as status 
        from TB_PRODUCT 
        <dynamic prepend="where">
            <isNotEmpty prepend="and" property="productId">
                ID = #productId#
            </isNotEmpty>
        </dynamic>
        order by ID
    </select>

 

应该注意的是这个字查询是有3个参数,一般来说一对多的情况是主键和外键的关系,这个方案就是为了解决这种可能的多参数的情况。

例子的关键是主表查询的时候使用 #areaId# as areaId,#status# as status 这样的方式,这样就可以在字查询中使用到status areaId这两个参数了。