I have a query that looks like this:
select
restaurant_id,
rank() OVER (PARTITION BY restaurant_id order by churn desc) as rank_churn,
churn,
orders,
rank() OVER (PARTITION BY restaurant_id order by orders desc) as rank_orders
from data
I would expect that this ranking function will order my data and provide a column that has 1,2,3,4 according to the values of the column.
However the outcome is always 1 in the ranking.
restaurant_id rank_churn churn orders rank_orders
2217 1 75 182 1
2249 1 398 896 1
2526 1 11 56 1
2596 1 89 139 1
What am I doing wrong?
Related
I have a table containing data that has a column named id that looks like below:
id
value 1
value 2
value 3
1
244
550
1000
1
251
551
700
1
540
60
1200
...
...
...
...
2
19
744
2000
2
10
903
100
2
44
231
600
2
120
910
1100
...
...
...
...
I want to take 50 sample rows per id that exists but if less than 50 exist for the group to simply take the entire set of data points.
For example I would like a maximum 50 data points randomly selected from id = 1, id = 2 etc...
I cannot find any previous questions similar to this but have tried taking a stab at at least logically working through the solution where I could iterate and union all queries by id and limit to 50:
SELECT * FROM (SELECT * FROM schema.table AS tbl WHERE tbl.id = X LIMIT 50) UNION ALL;
But it's obvious that you cannot use this type of solution because UNION ALL requires aggregating outputs from one id to the next and I do not have a list of id values to use in place of X in tbl.id = X.
Is there a way to accomplish this by gathering that list of unique id values and union all results or is there a more optimal way this could be done?
If you want to select a random sample for each id, then you need to randomize the rows somehow. Here is a way to do it:
select * from (
select *, row_number() over (partition by id order by random()) as u
from schema.table
) as a
where u <= 50;
Example (limiting to 3, and some row number for each id so you can see the selection randomness):
setup
DROP TABLE IF EXISTS foo;
CREATE TABLE foo
(
id int,
value1 int,
idrow int
);
INSERT INTO foo
select 1 as id, (1000*random())::int as value1, generate_series(1, 100) as idrow
union all
select 2 as id, (1000*random())::int as value1, generate_series(1, 100) as idrow
union all
select 3 as id, (1000*random())::int as value1, generate_series(1, 100) as idrow;
Selection
select * from (
select *, row_number() over (partition by id order by random()) as u
from foo
) as a
where u <= 3;
Output:
id
value1
idrow
u
1
542
6
1
1
24
86
2
1
155
74
3
2
505
95
1
2
100
46
2
2
422
33
3
3
966
88
1
3
747
89
2
3
664
19
3
In case you are looking to get 50 (or less) from each group of IDs then you can use windowing -
From question - "I want to take 50 sample rows per id that exists but if less than 50 exist for the group to simply take the entire set of data points."
Query -
with data as (
select row_number() over (partition by id order by random()) rn,
* from table_name)
select * from data where rn<=50 order by id;
Fiddle.
Your description of trying to get the UNION ALL without specifying all the branches ahead of time is aiming for a LATERAL join. And that is one way to solve the problem. But unless you have a table of all distinct ids, you would have to compute one on the fly. For example (using the same fiddle as Pankaj used):
with uniq as (select distinct id from test)
select foo.* from uniq cross join lateral
(select * from test where test.id=uniq.id order by random() limit 3) foo
This could be either slower or faster than the Window Function method, depending on your system and your data and your indexes. In my hands, it was quite a bit faster even with the need to dynamically compute the list of distinct ids.
I have a table with the following entries in them
id price quantity
1. 10 75
2. 10 75
3. 10 -150
4. 10 75
5. 10 -75
What I need to do is to update each row with a number that is the number of times the running total has been 0. In the above example, the cumulative totals would be
id. cum_total
1. 750
2. 1500
3. 0
4. 750
5. 0
Desired result
id price quantity seq
1. 10 75 1
2. 10 75 1
3. 10 -150 1
4. 10 75 2
5. 10 -75 2
I'm now lost in a spiral of CTEs and window functions and figured I'd ask the experts.
Thanks in advance :-)
Here is one option using analytic functions:
WITH cte AS (
SELECT *, CASE WHEN SUM(price*quantity) OVER (ORDER BY id) = 0 THEN 1 ELSE 0 END AS price_sum
FROM yourTable
),
cte2 AS (
SELECT *, LAG(price_sum, 1, 0) OVER (ORDER BY id) price_sum_lag
FROM cte
)
SELECT id, price, quantity, 1 + SUM(price_sum_lag) OVER (ORDER BY id) cumulative_total
FROM cte2
ORDER BY id;
Demo
You may try running each CTE in succession to see how the logic is working.
With window functions:
SELECT id, price, quantity,
coalesce(
sum(CASE WHEN iszero THEN 1 ELSE 0 END)
OVER (ORDER BY id
ROWS BETWEEN UNBOUNDED PRECEDING AND 1 PRECEDING),
0
) + 1 AS batch
FROM (SELECT id, price, quantity,
sum(price * quantity) OVER (ORDER BY id) = 0 AS iszero
FROM mytable) AS subq;
I'm trying to get this query to work properly...
select salary from agent
where salary > 75000
ORDER BY salary ASC
LIMIT (select ROUND(count(salary) * .75) as TwentyFifthTile from agent)
some addition information about the rows:
166 rows – 25%
331 rows – 50%
497 rows – 75%
662 rows – 100%
These rows have salary 75,000 plus:
235 / 662 = ~.35
.35 * 662 = ~235 rows.
I'm trying to get the above query to return back all the rows that have salary greater than 75,000 but are still in the first 497 rows. When I run the above query it returns all the rows starting at 75,000 and limited by a 497 row return constraint.
I'm not sure how I can just return salaries of greater than 75,000 that are in the first 497 rows of the limit constraint.
You can divide the total number of rows by the current row number to get this:
select salary
from (
select salary,
count(*) over () as total_count,
row_number() over (order by salary) as rn
from agent
where salary > 75000
) t
where (rn / total_count::numeric) <= 0.75
order by salary asc
Use row_number:
select salary, row_number() over (order by salary) row_num
from agent
where row_num < (select ROUND(count(salary) * .75) from agent)
and salary > 75000
Hi if I have the following table:
Person------Score-------Score_type
1 30 A
1 35 A
1 15 B
1 16 B
2 74 A
2 68 A
2 40 B
2 39 B
Where for each person and score type I want to pick out the maximum score to obtain a table like:
Person------Score-------Score_type
1 35 A
1 16 B
2 74 A
2 40 B
I can do this using multiple select statements, but this will be cumbersome, especially later on. so I was wondering if there is a function which can help me do this. I have used the parititon function before but only to label sequences in a table....
select person,
score_type,
max(score) as score
from scores
group by person, score_type
order by person, score_type;
With "partition function" I guess you mean window functions. They can indeed be used for this as well:
select person
score_type,
score
from (
select person,
score_type,
score,
row_number() over (partition by person, score_type order by score desc) as rn
from scores
) t
where rn = 1
order by person, score_type;
Using the max() aggregate function along with the grouping by person and score_type should do the trick.
I have multiple CTEs and I want to retrieve some information from a couple of them into next CTE.
So, I have this information from one of the CTEs:
PeriodID StarDate
1 2006-01-01
2 2007-04-25
3 2008-08-16
4 2009-12-08
5 2011-04-017
and this from other:
RecordID Date
100 2007-04-15
101 2008-05-21
102 2008-06-06
103 2008-07-01
104 2009-11-12
And I need to show in next one:
RecordID Date PeriodID
100 2007-04-15 1
101 2008-05-21 2
102 2008-06-06 2
103 2008-07-01 2
104 2009-11-12 3
I can use some case/when statement to define if date of record is in period 1,2,3,4 or 5 but it some situation I can have different numbers of periods return from the first CTE.
Is there a way to do this in the above context?
You can have multiple CTEs defined as follows, and then select from and join them as you would any other table.
with cte1 as (select * ...),
cte2 as (select * ...)
select
cte2.*,
periodid
from cte2
cross apply
(select top 1 * from cte1 where cte2.recorddate> cte1.startdate order by startdate desc) v