使用Impala获取连续旅行的次数

Question

样本数据

touristid|day
ABC|1
ABC|1
ABC|2
ABC|4
ABC|5
ABC|6
ABC|8
ABC|10

输出应为

touristid|trip
ABC|4

4后的逻辑是连续天数，连续天数sqq 1,1,2为第一，然后4,5,6为第二，然后8为第三，而10为第四我希望使用impala查询获得此输出

Answer 1

使用lag（）函数获取前一天，如果day-prev_day> 1，则计算new_trip_flag，然后计数（new_trip_flag）。

演示：

with table1 as ( 

select 'ABC' as touristid, 1  as day union all
select 'ABC' as touristid, 1  as day union all
select 'ABC' as touristid, 2  as day union all
select 'ABC' as touristid, 4  as day union all
select 'ABC' as touristid, 5  as day union all
select 'ABC' as touristid, 6  as day union all
select 'ABC' as touristid, 8  as day union all
select 'ABC' as touristid, 10 as day 
)

select touristid, count(new_trip_flag) trip_cnt
from 
(
select touristid, day, prev_day,
       case when (day-prev_day)>1 or prev_day is NULL then true end as new_trip_flag
from       
(
select touristid, day, 
       lag(day) over(partition by touristid order by day) prev_day
  from table1
)s
)s
group by touristid;

结果：

touristid   trip_cnt    
ABC 4