I am trying to group a record only if two of the fields repeat themselves.
I am designing a social sharing photo app. users can share, like and comment on thers photo. Each action (share, comment, like) will appear on their friends wall.
The Problem is that when a user do all the three actions, the picture appears three times instead of one with the three action on it.
Data in database is like this (activities_tb)
id | photoID | uiID | action | date
-------------------------------------------
1 | 1 | 2 | like | 01/01/2015
2 | 1 | 2 | share | 02/01/2015
3 | 1 | 4 | share | 03/01/2015
4 | 1 | 2 | comment | 04/01/2015
5 | 2 | 4 | like | 04/01/2015
6 | 2 | 2 | like | 05/01/2015
7 | 2 | 3 | share | 05/01/2015
8 | 2 | 4 | comment | 06/01/2015
8 | 3 | 3 | like | 07/01/2015
9 | 3 | 5 | like | 08/01/2015
10 | 3 | 5 | comment | 08/01/2015
The query result I want to get
id | photoID | uiID | action | date
-------------------------------------------
3 | 1 | 4 | share | 03/01/2015
4 | 1 | 2 | comment | 04/01/2015
6 | 2 | 2 | like | 05/01/2015
7 | 2 | 3 | share | 05/01/2015
8 | 2 | 4 | comment | 06/01/2015
8 | 3 | 3 | like | 07/01/2015
10 | 3 | 5 | comment | 08/01/2015
This is my statement
SELECT id, photoID, uiID, action, date
FROM activities_tb
GROUP BY photoID, uiID.
This combines all the photos by their id returning only three results
I will be glad if anyone can be of help, thank you
You can first select required ids and join on your table:
select tb.*
from activities_tb tb
join(select max(id) as id
from activities_tb
group by photoID, uiID) t on t.id = tb.id
You are looking for "SELECT DISTINCT"
SELECT DISTINCT photoID, uiID, action, date
FROM activities_tb
GROUP BY photoID, uiID.
Related
Consider the following sample table from a soccer tournament (let's call this table matches)
+----------+---------+--------------+
| match_id | club_id | goals_scored |
+----------+---------+--------------+
| 1 | 1 | 1 |
| 1 | 2 | 0 |
| 2 | 1 | 1 |
| 2 | 3 | 1 |
| 3 | 1 | 0 |
| 3 | 4 | 2 |
| 4 | 2 | 2 |
| 4 | 3 | 4 |
| 5 | 2 | 4 |
| 5 | 4 | 0 |
| 6 | 3 | 1 |
| 6 | 4 | 1 |
+----------+---------+--------------+
The resulting table we want should give us each club's total goals scored AND goals conceded:
+---------+--------------+----------------+
| club_id | goals_scored | goals_conceded |
+---------+--------------+----------------+
| 1 | 2 | 4 |
| 2 | 6 | 4 |
| 3 | 6 | 4 |
| 4 | 3 | 5 |
+---------+--------------+----------------+
Getting goals scored is straight forward enough...
SELECT SUM(goals_scored),
club_id
FROM matches
GROUP BY club_id
but I am absolutely flummoxed as to how to get it for each team's opponents.
I could, of course, construct a pretty complex array of subqueries to get there. If this were application-side work I'd likely just stuff it in a loop and iterate over each club to get there, but my use case requires a SQL answer if possible. Any thoughts?
edit: also if anyone has any better ideas on how to title this question, I'm all ears - I'm not really sure exactly how to describe this problem in the first place.
We can use a self-join approach here:
SELECT
m1.club_id,
SUM(m1.goals_scored) AS goals_scored,
SUM(m2.goals_scored) AS goals_conceded
FROM matches m1
INNER JOIN matches m2
ON m2.match_id = m1.match_id AND
m2.club_id <> m1.club_id
GROUP BY
m1.club_id
ORDER BY
m1.club_id;
This approach brings the goals conceded by each club to the other club, for each match, into a single row. We then just aggregate by club to get the two sums.
I have all those tables above.
car_model_tbl
-----------------------------
id | car_model_name|status |
-----------------------------
1 | seria_1 | 1 |
-----------------------------
2 | golf_4 | 1 |
-----------------------------
3 | C_Class | 1 |
-----------------------------
4 | golf_5 | 1 |
-----------------------------
5 | seria_2 | 0 |
-----------------------------
car_manufacturer_tbl
-------------------------
id |car_manufactu_name |
-------------------------
1 | bmw |
-------------------------
2 | volkswagen |
-------------------------
3 | mercedes |
-------------------------
car_service_tbl
---------------------------------
id | model_id| service_date |
---------------------------------
1 | 1 | 2018-03-10 |
---------------------------------
2 | 2 | 2018-02-10 |
---------------------------------
3 | 1 | 2018-01-10 |
---------------------------------
4 | 1 | 2017-12-10 |
---------------------------------
5 | 2 | 2017-12-10 |
---------------------------------
6 | 3 | 2018-02-10 |
---------------------------------
7 | 2 | 2018-01-10 |
---------------------------------
9 | 4 | 2018-03-10 |
---------------------------------
10 | 4 | 2018-02-10 |
---------------------------------
11 | 5 | 2018-02-10 |
---------------------------------
car_model_manufacturer_relation
-------------------------------------------------
id | model_id | manufactu_id| service_status |
-------------------------------------------------
1 | 1 | 1 | 1 |
-------------------------------------------------
2 | 5 | 1 | 1 |
-------------------------------------------------
3 | 2 | 2 | 1 |
-------------------------------------------------
4 | 4 | 1 | 1 |
-------------------------------------------------
5 | 2 | 2 | 1 |
-------------------------------------------------
6 | 3 | 3 | 1 |
-------------------------------------------------
I need to update car_model_manufacturer_relation.service_status = '0'
where car_service_tbl.service_date < "2018-03-01".
In this case car_model_manufacturer_relation.service_status of models 2, 3 and 5 should be set to '0' because every car_service_tbl.service_date for these models is smaller than "2018-03-01".
However, for models 1 and 4 car_model_manufacturer_relation.service_status should stay '1' because even that they have records smaller than "2018-03-01" they also have bigger dates ex. "2018-03-10".
I am trying to create a query for this but until now without success.
You'll need to nest a grouped query, to get the MAX date per model, and update from that.
update car_model_manufacturer_relation as cmmr,
(select model_id, max(service_date) as check_date
from car_service_tbl
group by model_id) as cst
set cmmr.service_status = '0'
where cmmr.model_id = cst.model_id
and cst.check_date < "2018-03-01"
Where you're using more than one table and the table names include underscores, I try and alias the tables to make the code a little shorter and easier on the eye, hence the use of cmmr and cst as table aliases.
The MAX date has also been renamed for clarity as check_date. You can of course name this anything you wish.
With sub query:
UPDATE car_model_manufacturer_relation c
LEFT join (SELECT model_id, service_date FROM car_service_tbl ORDER BY service_date DESC LIMIT 1) as s ON s.model_id = c.model_id
SET service_status=0
WHERE c.service_date < "2018-03-01"
#tyro - be careful with your solution, as a LEFT JOIN would update the service status to 0 when there wasn't a service date within the car_service_tbl. You would need to use a full join, rather than just the LEFT JOIN as you suggested in order to update the records correctly I feel.
I have a MySQL table like this:
+------+--------+--------+
| ID | UserID | Score |
+------+--------+--------+
| 1 | 3 | 12 |
| 2 | 3 | 11 |
| 3 | 3 | 12 |
| 4 | 2 | 14 |
| 5 | 4 | 8 |
| 6 | 2 | 13 |
+------+--------+--------+
From this I want to top 3 scores from entire table and a top score from particular user
+------+--------+--------+
| ID | UserID | Score |
+------+--------+--------+
| 4 | 2 | 14 |
| 6 | 2 | 13 |
| 3 | 3 | 12 |
| 5 | 4 | 8 |
+------+--------+--------+
Is this something I can get done in a single query?
Any help is appreciated
Thanks in advance!
spoiler alert ;)
(SELECT * FROM tableA ORDER BY score DESC LIMIT 3)
UNION
(SELECT * FROM tableB WHERE UserID = 4 ORDER BY score DESC LIMIT 1);
For certain definitions of "single query", sure... If you're willing to use sub queries or a union.
The best performance will probably come from two queries, but you can join them in a UNION for convenience if you wish.
i am loosing it over the following problem:
i have a table with participants and points. each participant can have up to 11 point entries of which i only want the sum of the top 6.
in this example lets say we want the top 2 of 3
+----+---------------+--------+
| id | participantid | points |
+----+---------------+--------+
| 1 | 1 | 11 |
+----+---------------+--------+
| 2 | 3 | 1 |
+----+---------------+--------+
| 3 | 3 | 4 |
+----+---------------+--------+
| 4 | 2 | 3 |
+----+---------------+--------+
| 5 | 1 | 5 |
+----+---------------+--------+
| 6 | 2 | 10 |
+----+---------------+--------+
| 7 | 2 | 9 |
+----+---------------+--------+
| 8 | 1 | 3 |
+----+---------------+--------+
| 9 | 3 | 4 |
+----+---------------+--------+
as a result i want something like
+---------------+--------+
| participantid | points |
+---------------+--------+
| 2 | 19 |
+---------------+--------+
| 1 | 16 |
+---------------+--------+
| 3 | 8 |
+---------------+--------+
(it should be ordered DESC by the resulting points)
is this at all possible with mysql? in one query?
oh and the resulting participant ids should be resolved into the real names from another 'partcipant' table where
+----+------+
| id | name |
+----+------+
| 1 | what |
+----+------+
| 2 | ev |
+----+------+
| 3 | er |
+----+------+
but that should be doable with a join at some point... i know...
Using one of the answers from ROW_NUMBER() in MySQL for row counts, and then modifying to get the top.
SELECT ParticipantId, SUM(Points)
FROM
(
SELECT a.participantid, a.points, a.id, count(*) as row_number
FROM scores a
JOIN scores b ON a.participantid = b.participantid AND cast(concat(a.points,'.', a.id) as decimal) <= cast(concat(b.points,'.', b.id) as decimal)
GROUP BY a.participantid, a.points, a.id
) C
WHERE row_number IN (1,2)
GROUP BY ParticipantId
Had an issue with ties until I arbitrarily broke them with the id
I have a query consisting of multiple joins and I am wondering whether it can be re-written to improve performance.
I have 2 tables as follows (I have removed non-important columns for this example):
slots
------------------------------------------
| id | name | slot_1 | slot_2 | slot_3 |
------------------------------------------
| 1 | Bob | 1 | 2 | 3 |
| 2 | Jim | 4 | 3 | 3 |
| 3 | Alf | 1 | 2 | 5 |
------------------------------------------
(There are 25 slots in total, each in it's own column)
slot_details
-----------------------------------
| id | stat_1 | stat_2 | stat_3 |
-----------------------------------
| 1 | 1 | 5 | 6 |
| 2 | 4 | 31 | 23 |
| 3 | 6 | 5 | 7 |
| 4 | 7 | 4 | 9 |
| 5 | 2 | 3 | 5 |
-----------------------------------
(There are 10 stats in total)
The query is as follows:
SELECT
slots.name,
slot_1_details.stat_1 AS slot_1_stat_1,
slot_1_details.stat_2 AS slot_1_stat_2,
slot_1_details.stat_3 AS slot_1_stat_3,
slot_2_details.stat_1 AS slot_2_stat_1,
slot_2_details.stat_2 AS slot_2_stat_2,
slot_2_details.stat_3 AS slot_2_stat_3,
slot_3_details.stat_1 AS slot_3_stat_1,
slot_3_details.stat_2 AS slot_3_stat_2,
slot_3_details.stat_3 AS slot_3_stat_3
FROM
slots
LEFT JOIN
slot_details AS slot_1_details
ON (
slot_1_details.id = slots.slot_1
)
LEFT JOIN
slot_details AS slot_2_details
ON (
slot_2_details.id = slots.slot_2
)
LEFT JOIN
slot_details AS slot_3_details
ON (
slot_3_details.id = slots.slot_3
)
WHERE (
slots.id = 1
)
The expected outcome of this query would be as follows:
| name | slot_1_stat_1 | slot_1_stat_2 | slot_1_stat_3 | slot_2_stat_1 | slot_2_stat_2 | slot_2_stat_3 | slot_3_stat_1 | slot_3_stat_2 | slot_3_stat_3 |
|bob | 1 | 5 | 6 | 4 | 31 | 23 | 6 | 5 | 7 |
Unfortunately I am not in a situation where I can change the tables.
Thank you for the help!
maybe
SELECT * FROM slots s LEFT JOIN slot_details sd ON s.id=sd.id
but i'm not sure because the query you posted is very confusing.
what are the keys of those tables?