Mybatis需要返回的数据参数中在数据表中没有对应的字段，自定义实体类和resultmap作为返回值类型

自定义实体类：因为需要做相关记录的统计，而表中没有统计字段

 public class TrafficJeevesDistrictCount {
//施工top5+1  按区域

	private String districtInfo;
	
	private String districtCount;

	public String getDistrictInfo() {
		return districtInfo;
	}

	public void setDistrictInfo(String districtInfo) {
		this.districtInfo = districtInfo;
	}

	public String getDistrictCount() {
		return districtCount;
	}

	public void setDistrictCount(String districtCount) {
		this.districtCount = districtCount;
	}
    	
}

Mapper映射文件中自定义resultmap:

统计的sql:top4
DISTRICT_CODE 是数据表中有的字段，count总记录没有，定义相关别名就行
district_info别名对应上面mapper映射中的column

  
   		select * from(
   			select  district_info,district_count,ROWNUM rn
   			from
   			(select DISTRICT_CODE as district_info,count(1) as district_count
   			from T_TRAFFIC_JEEVES
   			group by DISTRICT_CODE 
   			order by district_count desc )
   			where ROWNUM  4
   		) where rn = ]]> 1