问题
I want to find the count of rows between first and last occurrence of a value. However when there are five or more records of a different value between them, stop counting.
So if last occurrence is today and first occurrence is yesterday, the result would be 2 (today plus yesterday).
If last occurrence is today and first occurrence is 8 days ago AND there is no occurrence in between the two, the result would be '1'. If however there would be another occurrence 3 days ago, the result would be 4 (3+2+1 days ago plus today).
I hope that makes sense.
Here's my data
Date City Weather
==============================
2018-08-11 Ankara Sun
2018-08-10 Ankara Sun
2018-08-09 Ankara Sun
2018-08-08 Ankara Sun
2018-08-07 Ankara Sun
2018-08-06 Ankara Sun
2018-08-05 Ankara Rain
2018-08-04 Ankara Clouds
2018-08-03 Ankara Rain
2018-08-02 Ankara Sun
2018-08-01 Ankara Sun
2018-08-11 Cairo Clouds
2018-08-10 Cairo Sun
2018-08-09 Cairo Sun
2018-08-08 Cairo Sun
2018-08-07 Cairo Sun
2018-08-06 Cairo Sun
2018-08-05 Cairo Clouds
2018-08-04 Cairo Sun
2018-08-03 Cairo Sun
2018-08-02 Cairo Sun
2018-08-01 Cairo Sun
What I'm after is a query that returns for a given city and date the weather that day and the number of days since this weather first occurred. However, when there are gaps of five days or more, the count restarts from 1.
Like when queried for Ankara on the 11th Aug it would return 11 since it's been 11 days (including today) since Sun first occurred.
However for Cairo on the 11th Aug it would return 1 and not 7 because it's been 5+ days between Clouds on the 5th Aug and Clouds today.
I've tried many things with first_value(), LEAD, LAG and ROW_NUMBER but there is nothing that makes sense to how as it all failed miserably.
Here it is anyway...
select
city, val,datediff(day, min(datadate), '2018-10-30') + 1 as DaysPresent
from d
where val = last_val
group by city,val;
or...
select
date, city, weather, datediff(day,ca.prior,d.date)+1 as daysPresent
from d
cross apply (
select min(prev.date) as prior
from d as prev
where prev.city = d.city
and prev.date between dateadd(day,-4,d.date) and dateadd(day,0,d.date)
and prev.weather = d.weather
) ca
order by city,date
Expected Result
+----+---------------------+--------+---------+----------------+-------------+----------+----------------------------
| | date | city | weather | prior_the_same | prior_types |expected | why?
+----+---------------------+--------+---------+----------------+-------------+----------+----------------------------
| 1 | 11.08.2018 00:00:00 | Ankara | Sun | 5 | 2 | 11 | 11t day since 1st time Sun
| 2 | 10.08.2018 00:00:00 | Ankara | Sun | 4 | 3 | 10 | 10t day since 1st time Sun
| 3 | 09.08.2018 00:00:00 | Ankara | Sun | 7 | 3 | 9 | 9th day since 1st time Sun
| 4 | 08.08.2018 00:00:00 | Ankara | Sun | 7 | 3 | 8 | 8th day since 1st time Sun
| 5 | 07.08.2018 00:00:00 | Ankara | Sun | 6 | 3 | 7 | 7th day since 1st time Sun
| 6 | 06.08.2018 00:00:00 | Ankara | Sun | 5 | 3 | 6 | 6th day since 1st time Sun ( <5 days gap since last Sun keeps counting )
| 7 | 05.08.2018 00:00:00 | Ankara | Rain | 2 | 3 | 3 | 3rd day since 1st time Rain
| 8 | 04.08.2018 00:00:00 | Ankara | Clouds | 0 | 3 | 1 | 1st day Clouds
| 9 | 03.08.2018 00:00:00 | Ankara | Rain | 0 | 2 | 1 | 1st day Rain
| 10 | 02.08.2018 00:00:00 | Ankara | Sun | 1 | 0 | 2 | 2nd day since 1st time Sun
| 11 | 01.08.2018 00:00:00 | Ankara | Sun | 0 | 0 | 1 | 1st day Sun
| 12 | 11.08.2018 00:00:00 | Cairo | Clouds | 6 | 6 | 1 | 1st time Clouds ( >5 days gap since last Clouds resets the count )
| 13 | 10.08.2018 00:00:00 | Cairo | Sun | 7 | 1 | 10 | 10t day since 1st time Sun
| 14 | 09.08.2018 00:00:00 | Cairo | Sun | 7 | 1 | 9 | 9th day since 1st time Sun
| 15 | 08.08.2018 00:00:00 | Cairo | Sun | 7 | 1 | 8 | 8th day since 1st time Sun
| 16 | 07.08.2018 00:00:00 | Cairo | Sun | 6 | 1 | 7 | 7th day since 1st time Sun
| 17 | 06.08.2018 00:00:00 | Cairo | Sun | 5 | 1 | 6 | 6th day since 1st time Sun ( <5 days gap since last Sun keeps counting )
| 18 | 05.08.2018 00:00:00 | Cairo | Clouds | 0 | 4 | 1 | 1st time Clouds
| 19 | 04.08.2018 00:00:00 | Cairo | Sun | 3 | 0 | 4 | 4th day since 1st time Sun
| 20 | 03.08.2018 00:00:00 | Cairo | Sun | 2 | 0 | 3 | 3rd day since 1st time Sun
| 21 | 02.08.2018 00:00:00 | Cairo | Sun | 1 | 0 | 2 | 2nd day since 1st time Sun
| 22 | 01.08.2018 00:00:00 | Cairo | Sun | 0 | 0 | 1 | 1st day Sun
+----+---------------------+--------+---------+----------------+-------------+----------+----------------------------
回答1:
Latest
declare @day_range integer = 5;
select
t.date, t.city, t.weather
, datediff(day,ca1.prior_dt,t.date)+1 as prior_the_same
, twist.prior_types
, twist.prior_mx_dt
from mytable t
cross apply (
select count(prev.weather) as prior_types, max(prev.date) as prior_mx_dt
from mytable as prev
where prev.city = t.city
and prev.date between dateadd(day,-@day_range,t.date) and t.date
and prev.weather <> t.weather
) twist
cross apply (
select min(prev.date) as prior_dt
from mytable as prev
where prev.city = t.city
and (twist.prior_types < @day_range or prev.date >= twist.prior_mx_dt)
and prev.weather = t.weather
) ca1
order by t.city, t.date DESC
result:
+----+---------------------+--------+---------+----------------+-------------+---------------------+
| | date | city | weather | prior_the_same | prior_types | prior_mx_dt |
+----+---------------------+--------+---------+----------------+-------------+---------------------+
| 1 | 11.08.2018 00:00:00 | Ankara | Sun | 11 | 0 | NULL |
| 2 | 10.08.2018 00:00:00 | Ankara | Sun | 10 | 1 | 05.08.2018 00:00:00 |
| 3 | 09.08.2018 00:00:00 | Ankara | Sun | 9 | 2 | 05.08.2018 00:00:00 |
| 4 | 08.08.2018 00:00:00 | Ankara | Sun | 8 | 3 | 05.08.2018 00:00:00 |
| 5 | 07.08.2018 00:00:00 | Ankara | Sun | 7 | 3 | 05.08.2018 00:00:00 |
| 6 | 06.08.2018 00:00:00 | Ankara | Sun | 6 | 3 | 05.08.2018 00:00:00 |
| 7 | 05.08.2018 00:00:00 | Ankara | Rain | 3 | 3 | 04.08.2018 00:00:00 |
| 8 | 04.08.2018 00:00:00 | Ankara | Clouds | 1 | 3 | 03.08.2018 00:00:00 |
| 9 | 03.08.2018 00:00:00 | Ankara | Rain | 1 | 2 | 02.08.2018 00:00:00 |
| 10 | 02.08.2018 00:00:00 | Ankara | Sun | 2 | 0 | NULL |
| 11 | 01.08.2018 00:00:00 | Ankara | Sun | 1 | 0 | NULL |
| 12 | 11.08.2018 00:00:00 | Cairo | Clouds | 1 | 5 | 10.08.2018 00:00:00 |
| 13 | 10.08.2018 00:00:00 | Cairo | Sun | 10 | 1 | 05.08.2018 00:00:00 |
| 14 | 09.08.2018 00:00:00 | Cairo | Sun | 9 | 1 | 05.08.2018 00:00:00 |
| 15 | 08.08.2018 00:00:00 | Cairo | Sun | 8 | 1 | 05.08.2018 00:00:00 |
| 16 | 07.08.2018 00:00:00 | Cairo | Sun | 7 | 1 | 05.08.2018 00:00:00 |
| 17 | 06.08.2018 00:00:00 | Cairo | Sun | 6 | 1 | 05.08.2018 00:00:00 |
| 18 | 05.08.2018 00:00:00 | Cairo | Clouds | 1 | 4 | 04.08.2018 00:00:00 |
| 19 | 04.08.2018 00:00:00 | Cairo | Sun | 4 | 0 | NULL |
| 20 | 03.08.2018 00:00:00 | Cairo | Sun | 3 | 0 | NULL |
| 21 | 02.08.2018 00:00:00 | Cairo | Sun | 2 | 0 | NULL |
| 22 | 01.08.2018 00:00:00 | Cairo | Sun | 1 | 0 | NULL |
see it online: https://rextester.com/ZSHT63407
Original
with sample data of:
CREATE TABLE mytable(
Date DATE NOT NULL
,City VARCHAR(6) NOT NULL
,Weather VARCHAR(6) NOT NULL
);
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-11','Ankara','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-10','Ankara','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-09','Ankara','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-08','Ankara','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-07','Ankara','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-06','Ankara','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-05','Ankara','Rain');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-04','Ankara','Clouds');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-03','Ankara','Rain');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-02','Ankara','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-01','Ankara','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-11','Cairo','Clouds');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-10','Cairo','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-09','Cairo','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-08','Cairo','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-07','Cairo','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-06','Cairo','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-05','Cairo','Clouds');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-04','Cairo','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-03','Cairo','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-02','Cairo','Sun');
INSERT INTO mytable(Date,City,Weather) VALUES ('2018-08-01','Cairo','Sun');
Using this query:
declare @day_range integer = 7;
declare @ignore_range integer = 5;
select
t.date, t.city, t.weather
, datediff(day,ca1.prior_dt,t.date) as prior_the_same
, ca2.prior_types
from mytable t
cross apply (
select min(prev.date) as prior_dt
from mytable as prev
where prev.city = t.city
and prev.date between dateadd(day,-@day_range,t.date) and t.date
and prev.weather = t.weather
) ca1
cross apply (
select count(prev.weather) as prior_types
from mytable as prev
where prev.city = t.city
and prev.date between dateadd(day,-@day_range,t.date) and t.date
and prev.weather <> t.weather
) ca2
order by t.city, t.date DESC
The following is the result:
+----+---------------------+--------+---------+----------------+-------------+----------+
| | date | city | weather | prior_the_same | prior_types |expected? |
+----+---------------------+--------+---------+----------------+-------------+----------+
| 1 | 11.08.2018 00:00:00 | Ankara | Sun | 5 | 2 | |
| 2 | 10.08.2018 00:00:00 | Ankara | Sun | 4 | 3 | |
| 3 | 09.08.2018 00:00:00 | Ankara | Sun | 7 | 3 | |
| 4 | 08.08.2018 00:00:00 | Ankara | Sun | 7 | 3 | |
| 5 | 07.08.2018 00:00:00 | Ankara | Sun | 6 | 3 | |
| 6 | 06.08.2018 00:00:00 | Ankara | Sun | 5 | 3 | |
| 7 | 05.08.2018 00:00:00 | Ankara | Rain | 2 | 3 | |
| 8 | 04.08.2018 00:00:00 | Ankara | Clouds | 0 | 3 | |
| 9 | 03.08.2018 00:00:00 | Ankara | Rain | 0 | 2 | |
| 10 | 02.08.2018 00:00:00 | Ankara | Sun | 1 | 0 | |
| 11 | 01.08.2018 00:00:00 | Ankara | Sun | 0 | 0 | |
| 12 | 11.08.2018 00:00:00 | Cairo | Clouds | 6 | 6 | |
| 13 | 10.08.2018 00:00:00 | Cairo | Sun | 7 | 1 | |
| 14 | 09.08.2018 00:00:00 | Cairo | Sun | 7 | 1 | |
| 15 | 08.08.2018 00:00:00 | Cairo | Sun | 7 | 1 | |
| 16 | 07.08.2018 00:00:00 | Cairo | Sun | 6 | 1 | |
| 17 | 06.08.2018 00:00:00 | Cairo | Sun | 5 | 1 | |
| 18 | 05.08.2018 00:00:00 | Cairo | Clouds | 0 | 4 | |
| 19 | 04.08.2018 00:00:00 | Cairo | Sun | 3 | 0 | |
| 20 | 03.08.2018 00:00:00 | Cairo | Sun | 2 | 0 | |
| 21 | 02.08.2018 00:00:00 | Cairo | Sun | 1 | 0 | |
| 22 | 01.08.2018 00:00:00 | Cairo | Sun | 0 | 0 | |
+----+---------------------+--------+---------+----------------+-------------+----------+
Over more than one question you have expanded on your requirements. May I suggest you consider the above and decide if you can use the 2 calculations to arrive at the wanted final result. If you are still unable to come to a conclusion use the text table format to include the "expected result" as a new column
来源：https://stackoverflow.com/questions/53037973/sql-count-of-rows-between-first-and-last-occurrence-with-a-twist