此时from的查询结果此时查询全部null, 此时的t_date 也不会显示,有没有一个简单的办法,不管子查询是否为null,都会显示t_date 字段
select peer_id,type,datausage,live_r, ADDDATE(curdate(),-1) t_date
from(
select peer_id,type, sum(total_speed) datausage,live_r
from ds_transfer_data_session_202001
where start_time >= start_time >=1579305600 and start_time <= 1579392000
GROUP BY peer_id,type,live_r
) temp
where datausage > 0
GROUP BY peer_id,type,live_r;
https://blog.csdn.net/weixin_42245235/article/details/90449302