某个时间:date
时间段1:date1~date2
时间段2:date3~date4
时间段3:date5~date6
case
when date between date1 and date2 then '时间段'1'
when date between date3 and date4 then '时间段'2'
when date between date5 and date6 then '时间段'3'
end '时间段'