I've got the following Postgres query:
SELECT p_id as player_id, name as player_name
FROM Players
LEFT OUTER JOIN matches
ON Players.p_id = matches.player1 or Players.p_id = matches.player2
;
and it returns the following
player_id | player_name
-----------+-------------------
1 | Twilight Sparkle
1 | Twilight Sparkle
2 | Fluttershy
3 | Applejack
3 | Applejack
4 | Pinkie Pie
5 | "Rarity
5 | "Rarity
6 | Rainbow Dash
7 | Princess Celestia
7 | Princess Celestia
8 | Princess Luna
How can I end up with a table of unique p_id's with each one's name and the total of rows that p_id is in?
player_id | player_name | total_matches
-----------+-------------------+------
1 | Twilight Sparkle | 2
2 | Fluttershy | 1
3 | Applejack | 1
4 | Pinkie Pie | 1
5 | "Rarity | 2
6 | Rainbow Dash | 1
7 | Princess Celestia | 2
8 | Princess Luna | 1
You can achieve it using the group clause:
SELECT p_id as player_id, name as player_name, count(*) as total_matches
FROM Players
LEFT OUTER JOIN matches
ON Players.p_id = matches.player1 or Players.p_id = matches.player2
GROUP BY name
;
Related
I have table AnalysisForm
a_id| a_description | medical_card_id
-------------------------
1 | Analysis1 | 5
2 | Analysis2 | 3
3 | Analysis3 | 2
4 | Analysis4 | 1
and table DicomForm
d_id| d_description | medical_card_id
-------------------------
1 | DicomForm1 | 5
2 | DicomForm2 | 3
3 | DicomForm3 | 2
4 | DicomForm4 | 1
Now I want to get info by medical_card_id = 5 like this
form_id| form_description | medical_card_id
-------------------------
1 | DicomForm1 | 5
1 | Analysis1 | 5
How can I make it in Postgres?
I actually think that you want a union query here, rather than a join:
SELECT a_id AS form_id, a_description AS form_description, medical_card_id
FROM AnalysisForm
WHERE medical_card_id = 5
UNION ALL
SELECT d_id, d_description, medical_card_id
FROM DicomForm
WHERE medical_card_id = 5;
I have chapters table like this:
id | title | sort_number | book_id
1 | 'Chap 1' | 3 | 1
5 | 'Chap 2' | 6 | 1
8 | 'About ' | 1 | 1
9 | 'Chap 3' | 9 | 1
10 | 'Attack' | 1 | 2
Id is unique, sort_number is unique for same book(book_id)
1)How can load all data (3 rows) for 3 chapters (current, next and prev) sorted by sort_number if i have only current chapter id?
2)How can i load current chapter data (1 row) and only id's of next, prev if they exist?
This can be done using window functions
select id, title, sort_number, book_id,
lag(id) over w as prev_chapter,
lead(id) over w as next_chapter
from chapters
window w as (partition by book_id order by sort_number);
With your sample data that returns:
id | title | sort_number | book_id | prev_chapter | next_chapter
---+--------+-------------+---------+--------------+-------------
8 | About | 1 | 1 | | 1
1 | Chap 1 | 3 | 1 | 8 | 5
5 | Chap 2 | 6 | 1 | 1 | 9
9 | Chap 3 | 9 | 1 | 5 |
10 | Attack | 1 | 2 | |
The above query can now be used to answer both your questions:
1)
select id, title, sort_number, book_id
from (
select id, title, sort_number, book_id,
--first_value(id) over w as first_chapter,
lag(id) over w as prev_chapter_id,
lead(id) over w as next_chapter_id
from chapters
window w as (partition by book_id order by sort_number)
) t
where 1 in (id, prev_chapter_id, next_chapter_id)
2)
select *
from (
select id, title, sort_number, book_id,
lag(id) over w as prev_chapter_id,
lead(id) over w as next_chapter_id
from chapters
window w as (partition by book_id order by sort_number)
) t
where id = 1
Some background, I am making a table in Postgres 9.5 that counts the number of actions performed by a user and grouping these actions by month using date_trunc(). The counts for each individual action are divided into separate tables, following this format:
Feedback table:
id | month | feedback_counted
----+---------+-------------------
1 | 2 | 3
1 | 3 | 10
1 | 4 | 7
1 | 5 | 2
Comments table:
id | month | comments_counted
----+---------+-------------------
1 | 4 | 12
1 | 5 | 4
1 | 6 | 57
1 | 7 | 12
Ideally, I would like to do a FULL OUTER JOIN of these tables ON the "id" and "month" columns at the same time and produce this query:
Combined table:
id | month | feedback_counted | comments_counted
----+---------+--------------------+-------------------
1 | 2 | 3 |
1 | 3 | 10 |
1 | 4 | 7 | 12
1 | 5 | 2 | 4
1 | 6 | | 57
1 | 7 | | 12
However, my current query does not capture the feedback dates, displaying it like such:
Rollup table:
id | month | feedback_counted | comments_counted
----+---------+--------------------+-------------------
| | |
| | |
1 | 4 | 7 | 12
1 | 5 | 2 | 4
1 | 6 | | 57
1 | 7 | | 12
This is my current statement, note that it uses date_trunc in place of month. I add the action counts later, the main issue is somewhere here.
CREATE TABLE rollup_table AS
SELECT c.id, c.date_trunc
FROM comments_counted c FULL OUTER JOIN feedback_counted f
ON c.id = f.id AND c.date_trunc = f.date_trunc
GROUP BY c.id, c.date_trunc, f.id, f.date_trunc;
I'm a bit of a novice with SQL and am not sure how to fix this, any help would be appreciated.
Replace ON c.id = f.id AND c.month = f.month with USING(id, month).
SELECT id, month, feedback_counted, comments_counted
FROM comments c
FULL OUTER JOIN feedback f
USING(id, month);
id | month | feedback_counted | comments_counted
----+-------+------------------+------------------
1 | 2 | 3 |
1 | 3 | 10 |
1 | 4 | 7 | 12
1 | 5 | 2 | 4
1 | 6 | | 57
1 | 7 | | 12
(6 rows)
Test it in db<>fiddle.
USING() basically is the same as ON, just that if the 2 tables share the same column names, you can use USING() instead of ON to save some typing effort. That being said, using USING() won't work. In Postgresql (not sure about other sql versions), you still need to specify c.id, and c.month, even with USING(). And as long as you specify the columns, Postgresql will only pull the rows where the values of these columns exist. That's why you will have missing rows under the full outer join.
Here is a way that at least works for me.
SELECT COALESCE(c.id, f.id) AS id,
COALESCE(c.month, f.month) AS month,
feedback_counted,
comments_counted
FROM comments c
FULL OUTER JOIN feedback f
ON c.id = f.id AND c.month = f.month;
I have two table table:
I. Table 1 like this:
------------------------------------------
codeid | pos | neg | category
-----------------------------------------
1 | 10 | 3 | begin2016
1 | 3 | 5 | justhere
3 | 7 | 7 | justthere
4 | 1 | 1 | else
4 | 12 | 0 | begin2015
4 | 5 | 12 | begin2013
1 | 2 | 50 | now
2 | 5 | 33 | now
5 | 33 | 0 | Begin2011
5 | 11 | 7 | begin2000
II. Table 2 like this:
------------------------------------------
codeid | codedesc | codegroupid
-----------------------------------------
1 | road runner | 1
2 | bike warrior | 2
3 | lazy driver | 4
4 | clever runner | 1
5 | worker | 3
6 | smarty | 1
7 | sweety | 3
8 | sweeper | 1
I want to have one result like this having two (or more) conditions:
sum pos and neg where codegroupid IN('1', '2', '3')
BUt do not sum pos and neg if category like 'begin%'
So the result will like this:
------------------------------------------
codeid | codedesc | sumpos | sumneg
-----------------------------------------
1 | roadrunner | 5 | 55 => (sumpos = 3+2, because 10 have category like 'begin%' so doesn't sum)
2 | bike warrior | 5 | 33
4 | clever runner | 1 | 1
5 | worker | 0 | 0 => (sumpos=sumneg=0) becase codeid 5 category ilike 'begin%'
Group by codeid, codedesc;
Sumpos is sum(pos) where category NOT ILIKE 'begin%', BUT IF category ILKIE 'begin%' make all pos values become zero (0);
Sumpos is sum(neg) where category NOT ILIKE 'begin%', BUT IF category ILKIE 'begin%' make all neg values become zero;
Any ideas how to do it?
Try:
SELECT
b.codeid,
b.codedesc,
sum(CASE WHEN category LIKE 'begin%' THEN 0 ELSE a.pos END) AS sumpos,
sum(CASE WHEN category LIKE 'begin%' THEN 0 ELSE a.neg END) AS sumneg
FROM
table1 AS a
JOIN
table2 AS b ON a.codeid = b.codeid
WHERE b.codegroupid IN (1, 2, 3)
GROUP BY
b.codeid,
b.codedesc;
I need to list all the cities you can get to after stopping off at exactly one other city, starting off from any city of my choice. And list with it the distance to the final city and the intermediate city.
The tables in the database consist of cities, with the attributes:
| city_id | name |
1 Edinburgh
2 Newcastle
3 Manchester
citypairs:
| citypair_id | city_id |
1 1
1 2
2 1
2 3
3 2
3 3
and distances:
| citypair_id | distance |
1 1234
2 1324
3 1324
and trains:
| train_id | departure_city_id | destination_city_id |
1 1 2
2 2 3
3 1 3
4 3 2
I haven't put any of the data in but basically if a city.name is chosen at random by me I need to find out which cities I can get to from this city if I go via another city (i.e. in two journeys) and then the distance to the final and intermediate city.
How would you, or how should I, go about forming a query to return the desired table?
Edited to include data and a missing table! As an example you can go from Edinburgh(1) to Manchester(3) via Newcastle(2) and you can go from Edinburgh to Newcastle via Manchester, however you can not go from Manchester to Edinburgh via Newcastle (since a train departs from 3, arrives at 2, but no train from 2 arrives in 1) and this route should not be returned from the query. Apologies for any confusion beforehand.
I've got a CTE that builds a tree of all the destinations.
WITH RECURSIVE trip AS (
SELECT c.city_id AS start_city,
ARRAY[c.city_id] AS route,
cast(c.name AS varchar(100)) AS route_text,
c.city_id AS leg_start_city,
c.city_id AS leg_end_city,
0 AS trip_count,
0 AS leg_length,
0 AS total_length
FROM cities c
UNION ALL
SELECT
trip.start_city,
trip.route || t.destination_city_id,
cast(trip.route_text || ',' || c.name AS varchar(100)),
t.departure_city_id,
t.destination_city_id,
trip.trip_count + 1,
d.distance,
trip.total_length + d.distance
FROM trains t
INNER JOIN trip
ON t.departure_city_id = trip.leg_end_city
INNER JOIN citypairs cps
ON t.departure_city_id = cps.city_id
INNER JOIN citypairs cpe
ON t.destination_city_id = cpe.city_id AND
cpe.citypair_id = cps.citypair_id
INNER JOIN distances d
ON cps.citypair_id = d.citypair_id
INNER JOIN cities c
ON t.destination_city_id = c.city_id
WHERE NOT (array[t.destination_city_id] <# trip.route))
SELECT *
FROM trip
WHERE trip_count = 2
AND start_city = (SELECT city_id FROM cities WHERE name = 'Edinburgh');
The CTE starts from each city (in the non-recursive part at the start), then determines all the destination cities it can go to. It keeps a track of all the cities its been to in an array (the route column), so it won't loop back to itself again. As it progresses, it keeps track of the overall trip distance, and the number of trains taken (in trip_count).
As it goes through the tree, it keeps a running total of the distance.
This gives results of
| START_CITY | ROUTE | ROUTE_TEXT | LEG_START_CITY | LEG_END_CITY | TRIP_COUNT | LEG_LENGTH | TOTAL_LENGTH |
--------------------------------------------------------------------------------------------------------------------------------
| 1 | 1,2,3 | Edinburgh,Newcastle,Manchester | 2 | 3 | 2 | 1324 | 2558 |
| 1 | 1,3,2 | Edinburgh,Manchester,Newcastle | 3 | 2 | 2 | 1324 | 2648 |
If you change remove the final WHERE clause it'll show all the possible trips in the data, likewise you can change the trip_count to find all single train destinations etc.
| START_CITY | ROUTE | ROUTE_TEXT | LEG_START_CITY | LEG_END_CITY | TRIP_COUNT | LEG_LENGTH | TOTAL_LENGTH |
--------------------------------------------------------------------------------------------------------------------------------
| 1 | 1 | Edinburgh | 1 | 1 | 0 | 0 | 0 |
| 2 | 2 | Newcastle | 2 | 2 | 0 | 0 | 0 |
| 3 | 3 | Manchester | 3 | 3 | 0 | 0 | 0 |
| 1 | 1,2 | Edinburgh,Newcastle | 1 | 2 | 1 | 1234 | 1234 |
| 1 | 1,3 | Edinburgh,Manchester | 1 | 3 | 1 | 1324 | 1324 |
| 2 | 2,3 | Newcastle,Manchester | 2 | 3 | 1 | 1324 | 1324 |
| 3 | 3,2 | Manchester,Newcastle | 3 | 2 | 1 | 1324 | 1324 |
| 1 | 1,2,3 | Edinburgh,Newcastle,Manchester | 2 | 3 | 2 | 1324 | 2558 |
| 1 | 1,3,2 | Edinburgh,Manchester,Newcastle | 3 | 2 | 2 | 1324 | 2648 |
The cast( ... as varchar(100)) is a bit hacky, and I'm not sure why it was needed, but I haven't had a chance to get around that yet.
The SQL is here for testing: http://sqlfiddle.com/#!1/93964/24
The first part is easy:
SELECT c2.name
FROM cities AS c
JOIN trains t ON c.city_id=t.departure_city_id
JOIN trains t2 ON t.destination_city_id=t2.departure_city_id
JOIN cities AS c2 ON t2.destination_city_id=c2.city_id
WHERE c2.city_id!=c.city_id
AND c.name='Edinburgh';
http://sqlfiddle.com/#!12/a656f/14
In PG 9.1+ you could even do it with a recursive CTE for any number of cities in between. The distances are a little more complicated and you probably would be better off transforming city_pairs into actual pairs.