sum(if(overdue_days is not null,1,0)) 筛选逾期人数 concat(X...,'%')用于链接X...与% select pay_ability, concat(round(sum(if(overdue_days is not null,1,0))/count(customer_id)*100,1),'%') as overdue_ratio from loan_tb join customer_tb using(customer_id) group by 1 order by 2 desc