# 第一种情况不适合,因为timestampdiff(day, checkin_time, checkout_time) 会考虑到日期和时间的差异,因此在同一天但时间不同的情况下,也会正确计算出相差的天数。 # select # user_id, # room_id, # room_type, # if(timestampdiff(day,checkin_time,checkout_time) > 1,timestampdiff(day,checkin_time,checkout_time),0)as days # from checkin_tb ct # left join guest...