I have the following table/data:
| user_id | action_id | data |
-------------------------------------
| 10 | 1 | fly |
| 10 | 2 | train |
| 10 | 3 | fly |
| 10 | 4 | fly |
| 10 | 5 | fly |
| 10 | 6 | train |
| 10 | 7 | fly |
| 10 | 8 | train |
| 10 | 9 | fly |
| 10 | 10 | fly |
Is there a way in postgresql to count repeated continuous 'fly' occurrences? In this example, the results should be:
counts
------
1
3
1
2
Yes, it's possible, using the lag window function and a cumulative sum:
with FlagCTE as (
select t.action_id, t.data,
case when t.data = 'fly' and t.data = lag(t.data) over (order by t.action_id) then 0 else 1 end as Flag
from some_table t),
GroupCTE as (
select t.action_id,
t.data,
sum(t.Flag) over (order by t.action_id) as GroupId
from FlagCTE t
where t.data = 'fly')
select count(*) as counts
from GroupCTE t
group by t.GroupId
order by t.GroupId
SQLFiddle Demo
Related
As I know HAVING clause is used to filter rows for each group.
I have a table that stores scores of students.
create table sc
(
`classid` int,
`studentid` int,
`score` int
);
Here is the sample data:
+---------+-----------+-------+
| classid | studentid | score |
+---------+-----------+-------+
| 1 | 1 | 50 |
| 1 | 2 | 59 |
| 1 | 3 | 80 |
| 1 | 4 | 68 |
| 1 | 5 | 70 |
| 1 | 6 | 20 |
| 1 | 7 | 90 |
| 1 | 8 | 100 |
| 1 | 9 | 25 |
| 2 | 1 | 51 |
| 2 | 2 | 59 |
| 2 | 3 | 80 |
| 2 | 4 | 68 |
| 2 | 5 | 70 |
| 2 | 6 | 30 |
| 2 | 7 | 44 |
| 2 | 8 | 80 |
| 3 | 1 | 20 |
| 1 | 11 | 30 |
| 1 | 12 | 40 |
+---------+-----------+-------+
And I want to query the max score of each class, so I wrote this SQL statement:
select *
from sc
group by classid
having score = max(score);
But the output is not what I expect. The output only prints one row.
+---------+-----------+-------+
| classid | studentid | score |
+---------+-----------+-------+
| 3 | 1 | 20 |
+---------+-----------+-------+
If you have columns in your SELECT clause that are not being aggregated by an aggregate formula like sum(), max(), avg(), etc, then those columns also need to be present in your GROUP BY. Older versions of mysql are the only RDBMS that doesn't error when you miss this step. Instead of erroring, it will just grab whichever values it wishes and give you random results every time you run.
HAVING is one of the last steps to execute in SQL (just before ORDER BY). there's some nuance there with window functions and other stuff that executes late. Because of that doing score = max(score) doesn't make much sense. Either score is aggregated at this point or it is not. You can't compare both aggregated state and non-aggregated state of that column at the same time.
Instead you want a correlated subquery:
SELECT *
FROM t1 as dt
WHERE score =
(
SELECT MAX(score)
FROM t1 as dt2
WHERE dt.classid = dt2.classid
);
Alternatively you can use window functions:
SELECT *
FROM
(
SELECT classid,
studentid,
score,
MAX(score) OVER (PARTITION BY classid) as maxclassscore
FROM t1
) dt
WHERE score = maxclassscore;
Your code is not valid, but with your actual data you get only one result as only one has 100
SELECT * FROM sc WHERE score =
(select max(score) maxscore FROM sc);
classid | studentid | score
------: | --------: | ----:
1 | 8 | 100
db<>fiddle here
Suppose I have a table sorted by date as so:
+-------------+--------+
| DATE | VALUE |
+-------------+--------+
| 01-09-2020 | 5 |
| 01-15-2020 | 5 |
| 01-17-2020 | 5 |
| 02-03-2020 | 8 |
| 02-13-2020 | 8 |
| 02-20-2020 | 8 |
| 02-23-2020 | 5 |
| 02-25-2020 | 5 |
| 02-28-2020 | 3 |
| 03-13-2020 | 3 |
| 03-18-2020 | 3 |
+-------------+--------+
I want to group by changes in value within that given date range, and add a value that increments each time as an added column to denote that.
I have tried a number of different things, such as using the lag function:
SELECT value, value - lag(value) over (order by date) as count
GROUP BY value
In short, I want to take the table above and have it look like:
+-------------+--------+-------+
| DATE | VALUE | COUNT |
+-------------+--------+-------+
| 01-09-2020 | 5 | 1 |
| 01-15-2020 | 5 | 1 |
| 01-17-2020 | 5 | 1 |
| 02-03-2020 | 8 | 2 |
| 02-13-2020 | 8 | 2 |
| 02-20-2020 | 8 | 2 |
| 02-23-2020 | 5 | 3 |
| 02-25-2020 | 5 | 3 |
| 02-28-2020 | 3 | 4 |
| 03-13-2020 | 3 | 4 |
| 03-18-2020 | 3 | 4 |
+-------------+--------+-------+
I want to eventually have it all in one small table with the earliest date for each.
+-------------+--------+-------+
| DATE | VALUE | COUNT |
+-------------+--------+-------+
| 01-09-2020 | 5 | 1 |
| 02-03-2020 | 8 | 2 |
| 02-23-2020 | 5 | 3 |
| 02-28-2020 | 3 | 4 |
+-------------+--------+-------+
Any help would be very appreciated
you can use a combination of Row_number and Dense_rank functions to get the required results like below:
;with cte
as
(
select t.DATE,t.VALUE
,Dense_rank() over(partition by t.VALUE order by t.DATE) as d_rank
,Row_number() over(partition by t.VALUE order by t.DATE) as r_num
from table t
)
Select t.Date,t.Value,d_rank as count
from cte
where r_num = 1
You can use a lag and cumulative sum and a subquery:
SELECT value,
SUM(CASE WHEN prev_value = value THEN 0 ELSE 1 END) OVER (ORDER BY date)
FROM (SELECT t.*, LAG(value) OVER (ORDER BY date) as prev_value
FROM t
) t
Here is a db<>fiddle.
You can recursively use lag() and then row_number() analytic functions :
WITH t2 AS
(
SELECT LAG(value,1,value-1) OVER (ORDER BY date) as lg,
t.*
FROM t
)
SELECT t2.date,t2.value, ROW_NUMBER() OVER (ORDER BY t2.date) as count
FROM t2
WHERE value - lg != 0
Demo
and filter through inequalities among the returned values from those functions.
I have a table which has multiple records for the same id. Looks like this, and the rows are sorted by sequence number.
+----+--------+----------+----------+
| id | result | duration | sequence |
+----+--------+----------+----------+
| 1 | 12 | 7254 | 1 |
+----+--------+----------+----------+
| 1 | 12 | 2333 | 2 |
+----+--------+----------+----------+
| 1 | 11 | 1000 | 3 |
+----+--------+----------+----------+
| 1 | 6 | 5 | 4 |
+----+--------+----------+----------+
| 1 | 3 | 20 | 5 |
+----+--------+----------+----------+
| 2 | 1 | 230 | 1 |
+----+--------+----------+----------+
| 2 | 9 | 10 | 2 |
+----+--------+----------+----------+
| 2 | 6 | 0 | 3 |
+----+--------+----------+----------+
| 2 | 1 | 5 | 4 |
+----+--------+----------+----------+
| 2 | 12 | 3 | 5 |
+----+--------+----------+----------+
E.g. for id=1, i would like to sum the duration for all the rows before and include result=6, which is 7254+2333+1000+5. Same for id =2, it would be 230+10+0. Anything after the row where result=6 will be left out.
My expected output:
+----+----------+
| id | duration |
+----+----------+
| 1 | 10592 |
+----+----------+
| 2 | 240 |
+----+----------+
The sequence has to be in ascending order.
I'm not sure how I can do this in sql.
Thank you in advance!
I think you want:
select t2.id, sum(t2.duration)
from t
where t.sequence <= (select t2.sequence
from t t2
where t2.id = t.id and t2.result = 6
);
In PrestoDB, I would recommend window functions:
select id, sum(duration)
from (select t.*,
min(case when result = 6 then sequence end) over (partition by id) as sequence_6
from t
) t
where sequence <= sequence_6;
You can use a simple aggregate query with a condition that uses a subquery to recover the sequence corresponding to the record whose sequence is 6 :
SELECT t.id, SUM(t.duration) total_duration
FROM mytable t
WHERE t.sequence <= (
SELECT sequence
FROM mytable
WHERE id = t.id AND result = 6
)
GROUP BY t.id
This demo on DB Fiddle with your test data returns :
| id | total_duration |
| --- | -------------- |
| 1 | 10592 |
| 2 | 240 |
Basic group by query should solve your issue
select
id,
sum(duration) duration
from t
group by id
for the certain rows:
select
id,
sum(duration) duration
from t
where id = 1
group by id
if you want to include it in your result set
select id, duration, sequence from t
union all
select
id,
sum(duration) duration
null sequence
from t
group by id
I've posted several topics and every query had some problems :( Changed table and examples for better understanding
I have a table called PROD_COST with 5 fields
(ID,Duration,Cost,COST_NEXT,COST_CHANGE).
I need extra field called "groups" for aggregation.
Duration = number of days the price is valid (1 day=1row).
Cost = product price in this day.
-Cost_next = lead(cost,1,0).
Cost_change = Cost_next - Cost.
example:
+----+---------+------+-------------+-------+
|ID |Duration | Cost | Cost_change | Groups|
+----+---------+------+-------------+-------+
| 1 | 1 | 10 | -1,5 | 1 |
| 2 | 1 | 8,5 | 3,7 | 2 |
| 3 | 1 | 12.2 | 0 | 2 |
| 4 | 1 | 12.2 | -2,2 | 3 |
| 5 | 1 | 10 | 0 | 3 |
| 6 | 1 | 10 | 3.2 | 4 |
| 7 | 1 | 13.2 | -2,7 | 5 |
| 8 | 1 | 10.5 | -1,5 | 5 |
| 9 | 1 | 9 | 0 | 5 |
| 10 | 1 | 9 | 0 | 5 |
| 11 | 1 | 9 | -1 | 5 |
| 12 | 1 | 8 | 1.5 | 6 |
+----+---------+------+-------------+-------+
Now i need to group("Groups" field) by Cost_change. It can be positive,negative or 0 values.
Some kind guy advised me this query:
select id, COST_CHANGE, sum(GRP) over (order by id asc) +1
from
(
select *, case when sign(COST_CHANGE) != sign(isnull(lag(COST_CHANGE)
over (order by id asc),COST_CHANGE)) and Cost_change!=0 then 1 else 0 end as GRP
from PROD_COST
) X
But there is a problem: If there are 0 values between two positive or negative values than it groups it separately, for example:
+-------------+--------+
| Cost_change | Groups |
+-------------+--------+
| 9.262 | 5777 |
| -9.262 | 5778 |
| 9.262 | 5779 |
| 0.000 | 5779 |
| 9.608 | 5780 |
| -11.231 | 5781 |
| 10.000 | 5782 |
+-------------+--------+
I need to have:
+-------------+--------+
| Cost_change | Groups |
+-------------+--------+
| 9.262 | 5777 |
| -9.262 | 5778 |
| 9.262 | 5779 |
| 0.000 | 5779 |
| 9.608 | 5779 | -- Here
| -11.231 | 5780 |
| 10.000 | 5781 |
+-------------+--------+
In other words, if there's 0 values between two positive ot two negative values than they should be in one group, because Sequence: MINUS-0-0-MINUS - no rotation. But if i had MINUS-0-0-PLUS, than GROUPS should be 1-1-1-2, because positive valus is rotating with negative value.
Thank you for attention!
I'm Using Sql Server 2012
I think the best approach is to remove the zeros, do the calculation, and then re-insert them. So:
with pcg as (
select pc.*, min(id) over (partition by grp) as grpid
from (select pc.*,
(row_number() over (order by id) -
row_number() over (partition by sign(cost_change)
order by id
) as grp
from prod_cost pc
where cost_change <> 0
) pc
)
select pc.*, max(groups) over (order by id)
from prod_cost pc left join
(select pcg.*, dense_rank() over (order by grpid) as groups
from pcg
) pc
on pc.id = pcg.id;
The CTE assigns a group identifier based on the lowest id in the group, where the groups are bounded by actual sign changes. The subquery turns this into a number. The outer query then accumulates the maximum value, to give a value to the 0 records.
I have an issue where I need group a set of values and increase the group number when the variance between 2 columns is greater than or equal to 4, please see below.
UPDATE: I added a date column so you can view the order, but I need the group to update based off of the variance not the date.
+--------+-------+-------+----------+--------------+
| Date | Col 1 | Col 2 | Variance | Group Number |
+--------+-------+-------+----------+--------------+
| 1-Jun | 2 | 1 | 1 | 1 |
| 2-Jun | 1 | 1 | 0 | 1 |
| 3-Jun | 3 | 2 | 1 | 1 |
| 4-Jun | 4 | 1 | 3 | 1 |
| 5-Jun | 5 | 1 | 4 | 2 |
| 6-Jun | 1 | 1 | 0 | 2 |
| 7-Jun | 23 | 12 | 11 | 3 |
| 8-Jun | 12 | 11 | 1 | 3 |
| 9-Jun | 2 | 1 | 1 | 3 |
| 10-Jun | 13 | 4 | 9 | 4 |
| 11-Jun | 2 | 1 | 1 | 4 |
+--------+-------+-------+----------+--------------+
The group number is simply the number of times that 4 or greater appears in the variance column. You can get this using a correlated subquery:
select t.*,
(select 1 + count(*)
from table t2
where t2.date < t.date and t2.variance >= 4
) as GroupNumber
from table t;
In SQL Server 2012+, you can also do this using a cumulative sum:
select t.*,
sum(case when variance >= 4 then 1 else 0 end) over
(order by date rows between unbounded preceding and 1 preceding
) as GroupNumber
from table t;