You have a table like so:
id dollars dollars_rank points points_rank
1 20 1 35 1
2 18 2 30 3
3 10 3 33 2
I want a query that updates the table's rank columns (dollars_rank and points_rank) to set the rank for the given ID, which is just the row's index for that ID sorted by the relevant column in a descending order. How best to do this in PostgreSQL?
The window function dense_rank() is what you need - or maybe rank(). The UPDATE could look like this:
UPDATE tbl
SET dollars_rank = r.d_rnk
, points_rank = r.p_rnk
FROM (
SELECT id
, dense_rank() OVER (ORDER BY dollars DESC NULLS LAST) AS d_rnk
, dense_rank() OVER (ORDER BY points DESC NULLS LAST) AS p_rnk
FROM tbl
) r
WHERE tbl.id = r.id;
fiddle
NULLS LAST is only relevant if the involved columns can be NULL:
Sort by column ASC, but NULL values first?
Related
I have a data set as in the table below. I want to find the average of the maximum three values in a rolling 12 month window grouped by id.
id date value
id1 2020/01/01 500
id1 2021/02/01 300
id1 2021/03/01 150
id1 2021/08/01 100
id1 2021/12/01 400
id2 2020/01/01 50
id2 2020/02/01 900
id2 2021/12/01 100
So my expected output is:
id date value
id1 2020/01/01 500
id1 2021/02/01 300
id1 2021/03/01 225
id1 2021/08/01 183.33
id1 2021/12/01 283.33
id2 2020/01/01 50
id2 2020/02/01 500
id2 2021/12/01 100
I.e. for id1 2021/12/01: (400+300+150)/3 = 283.33 which is the average of the three largest values in a rolling 12 month window for group ID1.
I managed to get to this point:
CREATE TEMP FUNCTION avg_array(arr ANY TYPE) AS ((
SELECT AVG(val) FROM(
SELECT val FROM UNNEST(arr) val ORDER BY val DESC LIMIT 3)
)
);
SELECT id, date, avg_array(val_arr)
FROM (
SELECT
id, date, ARRAY_AGG(value) OVER (
PARTITION BY id
ORDER BY id, date DESC ROWS BETWEEN CURRENT ROW AND 11 FOLLOWING
) as val_arr
FROM `table` )
Which works, but I feel like there must be a better way to do this. Specifically, I can't figure out how to get the average of the maximum three from the OVER as well rather than creating a seperate function.
(If not possible to combine date window with finding maximum values, it would also be useful for me to know how to find the average of the maximum three in any group by group without creating a seperate function)
`
In your code, the year of the date in the “PARTITION BY id,EXTRACT(YEAR FROM date) “ statement is missing.
CREATE TEMP FUNCTION avg_array(arr ANY TYPE) AS ((
SELECT AVG(val) FROM(
SELECT val FROM UNNEST(arr) val ORDER BY val DESC LIMIT 3))
);
SELECT id, date, avg_array(val_arr)
FROM (
SELECT
id, date, ARRAY_AGG(value) OVER (
PARTITION BY id,EXTRACT(YEAR FROM date)
ORDER BY id, date DESC ROWS BETWEEN CURRENT ROW AND 11 FOLLOWING
) as val_arr
FROM `table` )
order by id,date asc
Here, you can see a sample code to get the maximum 3 numbers of a group:
select id,AVG(value) as vg from (
select id,date,value from (
select id, date, value from `table`
order by value desc) a limit 3
) b group by id
You can see more information about over function in this link.
Consider below approach
select id, date,
(select round(avg(value), 2) from (
select value from t.arr value
order by value desc
limit 3
)) value
from (
select *, array_agg(value) over last_12_month arr from table
window last_12_month as (partition by id
order by 12 * (extract(year from date)) + extract(month from date)
range between 11 preceding and current row
)
) t
if applied to sample data in your question - output is
select from_date_su_rela,to_date_su_rela from RELATION_T;
But the expectation is reducing -56 days from the first row from_date_su_rela and adding the +56 days to last(3rd) row to_date_su_rela. as below
I have written query as ,
select from_date_su_rela-56,to_date_su_rela+56 from RELATION_T; But its adding and reducing days from all the rows as below,
How to make it working as above 2nd image.
One option is to use the row_number analytic function sorting the data both ascending and descending to find the first and last row and then perform the addition and subtraction in a case statement
select case when rn_asc = 1
then from_date_su_rela - 56
else from_date_su_rela
end from_date_su_rela,
case when rn_desc = 1
then to_date_su_rela + 56
else to_date_su_rela
end to_date_su_rela
from (
select from_date_su_rela,
to_date_su_rela,
row_number() over (order by from_date_su_rela desc) rn_desc,
row_number() over (order by from_date_su_rela asc) rn_asc
from relation_t
)
I have a table segnature describing an item with a varchar field deno and a numeric field ord. A foreign key fk_collection tells which collection the row is part of.
I want to update field ord so that it contains the ordinal of that row per each collection, sorted by field deno.
E.g. if I have something like
[deno] ord [fk_collection]
abc 10
aab 10
bcd 10
zxc 20
vbn 20
Then I want a result like
[deno] ord [fk_collection]
abc 1 10
aab 0 10
bcd 2 10
zxc 1 20
vbn 0 20
I tried with something like
update segnature s1 set ord = (select count(*)
from segnature s2
where s1.fk_collection=s2.fk_collection and s2.deno<s1.deno
)
but query is really slow: 150 collections per about 30000 items are updated in 10 minutes about.
Any suggestion to speed up the process?
Thank you!
You can use a window function to generate the "ordinal" number:
with numbered as (
select deno, fk_collection,
row_number() over (partition by fk_collection order by deno) as rn,
ctid as id
from segnature
)
update segnature
set ord = n.rn
from numbered n
where n.id = segnature.ctid;
This uses the internal column ctid to uniquely identify each rows. The ctid comparison is quite slow, so if you have a real primary (or unique) key in that table, use that column instead.
Alternatively without the common table expression:
update segnature
set ord = n.rn
from (
select deno, fk_collection,
row_number() over (partition by fk_collection order by deno) as rn,
ctid as id
from segnature
) as n
where n.id = segnature.ctid;
SQLFiddle example: http://sqlfiddle.com/#!15/e997f/1
I have a table looks like,
x y
1 2
2 null
3 null
1 null
11 null
I want to fill the null value by conducting a rolling
function to apply y_{i+1}=y_{i}+x_{i+1} with sql as simple as possible (inplace)
so the expected result
x y
1 2
2 4
3 7
1 8
11 19
implement in postgresql. I may encapsulate it in a window function, but the implementation of custom function seems always complex
WITH RECURSIVE t AS (
select x, y, 1 as rank from my_table where y is not null
UNION ALL
SELECT A.x, A.x+ t.y y , t.rank + 1 rank FROM t
inner join
(select row_number() over () rank, x, y from my_table ) A
on t.rank+1 = A.rank
)
SELECT x,y FROM t;
You can iterate over rows using a recursive CTE. But in order to do so, you need a way to jump from row to row. Here's an example using an ID column:
; with recursive cte as
(
select id
, y
from Table1
where id = 1
union all
select cur.id
, prev.y + cur.x
from Table1 cur
join cte prev
on cur.id = prev.id + 1
)
select *
from cte
;
You can see the query at SQL Fiddle. If you don't have an ID column, but you do have another way to order the rows, you can use row_number() to get an ID:
; with recursive sorted as
(
-- Specify your ordering here. This example sorts by the dt column.
select row_number() over (order by dt) as id
, *
from Table1
)
, cte as
(
select id
, y
from sorted
where id = 1
union all
select cur.id
, prev.y + cur.x
from sorted cur
join cte prev
on cur.id = prev.id + 1
)
select *
from cte
;
Here's the SQL Fiddle link.
I have a table with the following data
Bldg Suit SQFT Date
1 1 1,000 9/24/2012
1 1 1,500 12/31/2011
1 2 800 8/31/2012
1 2 500 10/1/2005
I want to write a query that will sum the max date for each suit record, so the desired result would be 1,800, and must be in one cell/row. This will ultimately be part of subquery, I am just not getting what I expect with the queries I have writtren so far.
Thanks in advance.
You can use the following (See SQL Fiddle with Demo):
select sum(t1.sqft) Total
from yourtable t1
inner join
(
select max(dt) mxdt, suit, bldg
from yourtable
group by suit, bldg
) t2
on t1.dt = t2.mxdt
and t1.bldg = t2.bldg
and t1.suit = t2.suit
; With Data As
(
Select Bldg, Suit, SQFT, Row_Number() Over (Partition By Bldg, Suit Order By Date DESC) As RowID
From YourTableNameHere
)
Select Bldg, Sum(SQFT) As TotalSQFT
From Data
Where RowId = 1
Group By Bldg