Teradata数据库查询时error，
在Teradata数据库查询以下sql语句时：
select caller.*,catcher.*
from
(select top 300 c_usr_nbr,sum(int_cnt),count(c_usr_nbr)
from sna.yk_gmr_frd_out
group by c_usr_nbr
order by sum(int_cnt) desc) caller
inner join
(select top 300 vc_b_nbr,sum(int_cnt),count(vc_b_nbr)
from sna.yk_gmr_frd_out
group by vc_b_nbr
order by sum(int_cnt) desc) catcher
on caller.c_usr_nbr=catcher.vc_b_nbr
报错如下：
error select failed 3706 syntax error： all expressions in a derived table must hava an explicit name。后来发现是由于连接的2个表中，字段sum(int_cnt)和字段count(c_usr_nbr)冲突，修改如下：
select caller.*,catcher.*
from
(select top 300 c_usr_nbr,sum(int_cnt) as sum1,count(c_usr_nbr) as count1
from sna.yk_gmr_frd_out
group by c_usr_nbr
order by sum(int_cnt) desc) caller
inner join
(select top 300 vc_b_nbr,sum(int_cnt) as sum2,count(vc_b_nbr) as count2
from sna.yk_gmr_frd_out
group by vc_b_nbr
order by sum(int_cnt) desc) catcher
on caller.c_usr_nbr=catcher.vc_b_nbr
order by sum1 desc;