Mybatis高级功能

沈阳格力专卖店

应用场景：
应用所取的结果集中需要嵌入别的SQL的结果集。

<resultMap type="com.kevin.wallet.dto.CardsDetailResponse" id="cardsDetailResponse">
<result property="walletID" column="wallet_id"/>
<result property="totalAmount" column="totalAmount"/>
<result property="pageNumber" column=""/>
<result property="totalNumber" column="totalNumber"/>
<association property="bailianAmount"  column="{id=WALLET_ID}" select="getBailianAmount" />
<association property="okAmount" column="{id=WALLET_ID}" select="okAmount" />
<collection property="cards" ofType="com.kevin.wallet.dto.ListCardInforResponse" >
<result property="cardNo" column="CARD_ID"/>  
<result property="cardName" column="CARD_NAME"/>  
<result property="balanceValue" column="BALANCE_VALUE"/>  
<result property="validateTill" column="FROZEN_AT"/>  
<result property="cardType" column="TYPE"/>  
<result property="isForbidden" column="IS_FORBIDDEN"/>  
<result property="alias" column="CARD_ALIAS"/>  
<result property="status" column="STATUS"/>
<result property="order" column="CARD_ORDER"/>  
</collection>
</resultMap>



<select id="getBailianAmount" parameterType="java.util.Map" resultType="java.math.BigDecimal">
SELECT  
SUM(BALANCE_VALUE) as BAILIANAMOUNT
FROM(
SELECT
*
FROM
AVALIABLE_MEMBER_CARD member
WHERE
member.WALLET_ID = #{id}
UNION
SELECT
*
FROM
AVALIABLE_PRODUCT_CARD product
where
product.WALLET_ID = #{id}
)where TYPE=1 or TYPE=3
GROUP BY  WALLET_ID
</select>


association 是对应数据库中一对一的关系，它会将getBailianAmount sql语句的返回值赋给bailianAmount这个属性。column这个属性用于设置getBailianAmount  sql语句的传入参数。column="{id=WALLET_ID}" 意思是将WALLET_ID列作为getBailianAmount sql语句的参数，id对应map的key， sql语句通过#{id}来获取该key的值。