解决IBatis中的多对一映射n+1问题

<? xml version="1.0" encoding="UTF-8" ?>
<! DOCTYPE sqlMap PUBLIC "-//iBATIS.com//DTD SQL Map 2.0//EN" 
"http://www.ibatis.com/dtd/sql-map-2.dtd" >

< sqlMap  namespace ="specialtopic" >

    .................................
    
    
     < resultMap  id ="top-Video-column1"  class ="moxtv.central.po.Video" >
         < result  property ="videoId"  column ="videoId"   />
         < result  property ="title"  column ="title"   />
         < result  property ="timeSpan"  column ="timeSpan"   />
         
         < result  property ="user.loginName"  column ="loginName"   />
         < result  property ="videoReport.viewedCount"  column ="viewedCount"   />
        
     </ resultMap >
        
     < statement  id ="getTopVideoListByColumn1"  resultMap ="top-Video-column1"  cacheModel ="getTopVideoListByColumn1-cache" >
        select v.videoId,v.title,v.timeSpan,tu.loginName,vr.viewedCount 
        from top_baby_video tbv
        inner join video v on tbv.videoId=v.videoId
        inner join video_report vr on v.videoId=vr.videoId  
        inner join tvUser tu on v.tvUserId=tu.tvUserId
     </ statement >
    ............................
</ sqlMap >