select date_format(t_time,'%Y-%m') time # substr(t_time,1,7) time ,sum(t_amount) total from trade t1 left join customer t2 on t1.t_cus=t2.c_id where c_name='Tom' and year(t_time)=2023 and t_type=1 group by date_format(t_time,'%Y-%m') order by date_format(t_time,'%Y-%m'); # 1.SELECT列表中的非聚合列必须出现在GROUP...