一对多映射解析_n+1问题

iBATIS一对多映射之中继VO如下属性：

public class RelayInfoVO {
  //中继信息
  private String bswitcherNames;//本端局
  private String dswitcherNames;//对端局
  private String signalStatCount;//信令数
  private String relayStatCount;//中继数
  private List signalVO;//信令List,用来存放信令List的

  ……

iBATIS一对多映射信令VO如下属性：

public class SignalInfoVO {
  //信令信息
  private String bswitchers;//本端局
  private String dswitchers;//对端局
  private String signalType;//信令类型
  private String signalCount;//信令个数

  ……

iBATIS的XML如下配置：

注：为中继

VO,column="{bswitcherNames=bswitcherName,dswitcherNames=DSWITCHERNAME}" 是为select="getSignalInfo"所传递的参数。select="getSignalInfo"为所要调用的SELECT查询语句。

﹤resultMap id="RelayInfoVO-Result-list" class="com.harvest.ermis.rscount.domain.RelayInfoVO"﹥
  ﹤result property="bswitcherNames" column="BSWITCHERNAME" nullValue=""/﹥
  ﹤result property="dswitcherNames" column="DSWITCHERNAME" nullValue=""/﹥
  ﹤result property="signalStatCount" column="SIGNALSTATCOUNT" nullValue=""/﹥
  ﹤result property="relayStatCount" column="RELAYSTATCOUNT" nullValue=""/﹥
  ﹤result property="signalVO" column="{bswitcherNames=bswitcherName,dswitcherNames=DSWITCHERNAME}" select="getSignalInfo"/﹥
﹤/resultMap﹥

注：为信令VO

﹤resultMap id="SignalInfoVO-Result-list" class="com.harvest.ermis.rscount.domain.SignalInfoVO"﹥
  ﹤result property="bswitchers" column="BSWITCHERS" nullValue=""/﹥
  ﹤result property="dswitchers" column="DSWITCHERS" nullValue=""/﹥
  ﹤result property="signalType" column="SIGNALTYPE" nullValue=""/﹥
  ﹤result property="signalCount" column="SIGCOUTN" nullValue=""/﹥
﹤/resultMap﹥



﹤select id="getRSInfo" resultMap="RelayInfoVO-Result-list"﹥

    ……

﹤/select﹥


elect id="getSignalInfo" resultMap="SignalInfoVO-Result-list"﹥
      select c.switcherName as BSWITCHERS,b.switcherName as DSWITCHERS,linkType as SIGNALTYPE,count(*) as SIGCOUTN
      where
        c.switcherName=#bswitcherNames#
      and b.switcherName=#dswitcherNames#
      group by b.switcherName,b.ATTACHING,c.switcherName,linktype
      order by c.switcherName,b.SWITCHERORDER,linktype
﹤/select﹥

上面会有N+1问题，但提供了传多参方法。

 

下面解决List<String>映射问题：

<resultMap class="TaskUser" id="TaskUserResult" groupBy="patNo">
   <result property="patNo" column="T_NO" />
   <result property="userList" resultMap="PatTask.StringList"/>
  </resultMap>
 
  <resultMap id="StringList" class="java.lang.String">
   <result property="" column="NAME"/>
  </resultMap>

 

<select id="selectAllPatNoWithUser" resultMap="TaskUserResult">
   <![CDATA[
    select t.T_NO,u.NAME FROM pat_task t,tblUser u where t.T_ExUID=u.id;
   ]]>
  </select>