子查询的有关问题select id,(select top 1 username from stu b where a.id=b.id) as usera from stu a group by id怎么取得其中子查询的值呢

子查询的问题select id,(select top 1 username from stu b where a.id=b.id) as usera from stu a group by id如何取得其中子查询的值呢
一个数据库查询

select   id,(select   top   1   username   from   stu   b   where   a.id=b.id)   as   usera   from   stu   a   group   by   id

可是在java里用ResultSet   rs  
rs.getObject(2)来取得其中子查询的结果usera,提示报错

在java里该如何得到子查询的结果呢?

------解决方案--------------------
select id,(select top 1 username from stu b where a.id=b.id) as usera from stu a group by id
应该没问题
rs.getObject(2)　是得到整形的数据
rs.getString( "usera ");才是得到数据的字段名
------解决方案--------------------
vrs.getString( "usera ");