I'm breaking my head trying to modify this query(thx sgeddes) in order to
get at result not only from db_events.events fields, instead join it with some db_system.devices fields
SELECT e.*
FROM db_events.events e
JOIN (
SELECT Max(id) MaxId, device_id
FROM db_events.events
GROUP BY device_id ) e2 on e.Id = e2.MaxId AND e.device_id = e2.device_id
WHERE e.device_id IN (
SELECT device_id
FROM db_system.devices
WHERE vendor = 1)
ORDER BY e.id DESC
How can I get it without repeat the subquery:
SELECT *
FROM db_system.devices
WHERE vendor = 1
I need get db_system.devices.brand and db_system.devices.model joined with final results, and
I tried to modify it step to step, I tried with temporary tables, I suspect it should be something simple, but I have not been able to do it, of course thank you very much...
is this what you want?
SELECT e.*, a.*
FROM db_events.events e
INNER JOIN
(
SELECT Max(id) MaxId, device_id
FROM db_events.events
GROUP BY device_id
) e2 on e.Id = e2.MaxId AND
e.device_id = e2.device_id
INNER JOIN db_system.devices a
ON e.device_id = a.device_id AND
a.vendor = 1
ORDER BY e.id DESC
the condition a.vendor = 1 can also be moved on WHERE clause and the result is still the same since you are using INNER JOIN
SELECT ....
FROM .... JOIN ....
WHERE a.vendor = 1
ORDER BY ...
Related
Following query shows the results I need from table pointsList (latest records per user grouped by column idMatch)
select * from pointsList p
inner join ( select idMatch, max(datePointsCalculated ) as MaxDate from pointsList group by idMatch ) tm
on p.idMatch = tm.idMatch and p.datePointsCalculated = tm.MaxDate
order by p.idMatch ASC
But now I want to also select some additional information about the user (from table users). My naive way to tackle this was by making a new inner join like this:
select * from pointsList p, users u
inner join users
on u.idUser = p.idUser
inner join ( select idMatch, max(datePointsCalculated ) as MaxDate from pointsList group by idMatch ) tm
on p.idMatch = tm.idMatch and p.datePointsCalculated = tm.MaxDate
order by p.idMatch ASC
But I get the error message "unknown column 'p.idUser' in on clause". I tried using users.idUser and pointsList.idUser and other combinations (renaming pointsList in the on-clouse) but I always get the unknown column error (pointsList.idUser really does exist). Anyone could explain what I am doing wrong? I would like to extend this query to another table as well.
Thank you in advance!
Comma , priority in FROM clause is less than JOIN priority. And your query acts as:
select * from pointsList p,
(
users u
inner join users
on u.idUser = p.idUser
inner join ( select idMatch, max(datePointsCalculated ) as MaxDate from pointsList group by idMatch ) tm
on p.idMatch = tm.idMatch and p.datePointsCalculated = tm.MaxDate
)
order by p.idMatch ASC
Of course, table pointsList AS p is not accessible within the parenthesis.
Use CROSS JOIN instead of comma:
select * from pointsList p
CROSS JOIN users u
inner join users
on u.idUser = p.idUser
inner join ( select idMatch, max(datePointsCalculated ) as MaxDate from pointsList group by idMatch ) tm
on p.idMatch = tm.idMatch and p.datePointsCalculated = tm.MaxDate
order by p.idMatch ASC
I am tying to ordering a sub query before grouping it. The problem is that the sub query is order as if we take it just like a query. But as sub query order by does nothing.
Here's the query:
SELECT * FROM (
SELECT
a.id,
citypair,
a.season,
airline,
class,
fare,
rbd,
season_from,
season_to,
schedule_id,
cp.departure_id,
cp.destination_id,
sch.date_time
FROM tarifftool_price_log as a
JOIN tarifftool_seasons as b ON a.seasonId = b.id
JOIN tarifftool_citypairs as cp ON citypair = cp.id
JOIN tarifftool_schedule_queue AS sch ON schedule_id = sch.id
WHERE b.date = '12/26' AND class = 'b' ORDER BY schedule_id DESC) as qq
GROUP BY citypair, airline
Now i'am just trying as a result get a ordered query. If I do achieve this, i will have no problem grouping my data.
Use Row_Number in sub query
ROW_NUMBER() OVER(ORDER BY schedule_id)
SELECT * FROM (
SELECT
ROW_NUMBER() OVER(ORDER BY schedule_id DESC ) as RowId,
a.id,
citypair,
a.season,
airline,
class,
fare,
rbd,
season_from,
season_to,
schedule_id,
cp.departure_id,
cp.destination_id,
sch.date_time
FROM tarifftool_price_log as a
JOIN tarifftool_seasons as b ON a.seasonId = b.id
JOIN tarifftool_citypairs as cp ON citypair = cp.id
JOIN tarifftool_schedule_queue AS sch ON schedule_id = sch.id
WHERE b.date = '12/26' AND class = 'b' ) as qq
GROUP BY citypair, airline
Here is a sample SQL dump: https://gist.github.com/JREAM/99287d033320b2978728
I have a SELECT that grabs a bundle of users.
I then do a foreach loop to attach all the associated tree_processes to that user.
So I end up doing X Queries: users * tree.
Wouldn't it be much more efficient to fetch the two together?
I've thought about doing a LEFT JOIN Subselect, but I'm having a hard time getting it correct.
Below I've done a query to select the correct data in the SELECT, however I would have to do this for all 15 rows and it seems like a TERRIBLE waste of memory.
This is my dirty Ateempt:
-
SELECT
s.id,
s.firstname,
s.lastname,
s.email,
(
SELECT tp.id FROM tree_processes AS tp
JOIN tree AS t ON (
t.id = tp.tree_id
)
WHERE subscribers_id = s.id
ORDER BY tp.id DESC
LIMIT 1
) AS newest_tree_id,
#
# Don't want to have to do this below for every row
(
SELECT t.type FROM tree_processes AS tp
JOIN tree AS t ON (
t.id = tp.tree_id
)
WHERE subscribers_id = s.id
ORDER BY tp.id DESC
LIMIT 1
) AS tree_type
FROM subscribers AS s
INNER JOIN scenario_subscriptions AS ss ON (
ss.subscribers_id = s.id
)
WHERE ss.scenarios_id = 1
AND ss.completed != 1
AND ss.purchased_exit != 1
AND deleted != 1
GROUP BY s.id
LIMIT 0, 100
This is my LEFT JOIN attempt, but I am having trouble getting the SELECT values
SELECT
s.id,
s.firstname,
s.lastname,
s.email,
freshness.id,
# freshness.subscribers_id < -- Cant get multiples out of the LEFT join
FROM subscribers AS s
INNER JOIN scenario_subscriptions AS ss ON (
ss.subscribers_id = s.id
)
LEFT JOIN ( SELECT tp.id, tp.subscribers_id AS tp FROM tree_processes AS tp
JOIN tree AS t ON (
t.id = tp.tree_id
)
ORDER BY tp.id DESC
LIMIT 1 ) AS freshness
ON (
s.id = subscribers_id
)
WHERE ss.scenarios_id = 1
AND ss.completed != 1
AND ss.purchased_exit != 1
AND deleted != 1
GROUP BY s.id
LIMIT 0, 100
In the LEFT JOIN you are using 'freshness' as the table alias. This in you select you need to additionally state what column(s) you want from it. Since there is only one column (id) you need to add:
freshness.id
to the select clause.
Your ON clause of the left join looks pretty dodgy too. Maybe freshness.id = ss.subscribers_id?
Cheers -
i have these tables :
notice
id INT
cdate DATETIME
...
theme
id
name
notice_theme
id_notice
id_theme
I want to get the latest notices for each theme.
SELECT id_theme, n.id
FROM notice_theme
LEFT JOIN (
SELECT id, cdate
FROM notice
ORDER BY cdate DESC
) AS n ON notice_theme.id_notice = n.id
GROUP BY id_theme
The result is not good. An idea ? Thanks.
There are so many ways to solve this but I'm used to do it this way. An extra subquery is needed to separately calculate the latest cDate for every ID.
SELECT a.*, c.*
FROM theme a
INNER JOIN notice_theme b
ON a.ID = b.id_theme
INNER JOIN notice c
ON b.id_notice = c.ID
INNER JOIN
(
SELECT a.id_theme, MAX(b.DATE_CREATE) max_date
FROM notice_theme a
INNER JOIN notice b
ON a.ID_Notice = b.ID
GROUP BY a.id_theme
) d ON b.id_theme = d.id_theme AND
c.DATE_CREATE = d.max_date
SQLFiddle Demo
I have the following MySQL tables (Simplified)
DRIVER (D)
----------
id (PK)
name
RACE (RA)
---------
id (PK)
date
RESULT (RE)
-----------
id (PK)
raceid (FK -> RACE.id)
driverid (FK -> DRIVER.id)
bestRound
averageRound
I want to be able to list all drivers with their numRaces, firstRace, lastRace, bestRound, bestAverageRound and the dates on which their bestRound and bestAverageRound happened. I'm having problems with the last two, the dates for bestRound and bestAverageRound.
This is what I have so far:
SELECT D.name, COUNT(DISTINCT RE.raceid) AS numRaces, min(RA.date) AS firstRace,
max(RA.date) AS lastRace, min(RE.bestRound) AS bestRound,
min(RE.averageRound) AS bestAverageRound
FROM DRIVER D
JOIN RESULT RE ON RE.driverid = D.id
JOIN RACE RA ON RA.id = RE.raceid
GROUP BY D.id
ORDER BY D.name
This is working correctly. But how do I proceed to select the dates from the RACE table on which the bestRound and bestAverageRound occurred? Thanks for your time.
Try this solution:
SELECT
a.*, b.date AS bestRoundDate, c.date AS bestAverageRoundDate
FROM
(
SELECT
d.id,
d.name,
COUNT(DISTINCT re.raceid) AS numRaces,
MIN(ra.date) AS firstRace,
MAX(ra.date) AS lastRace,
MIN(re.bestRound) AS bestRound,
MIN(re.averageRound) AS bestAverageRound
FROM driver d
INNER JOIN result re ON d.id = re.driverid
INNER JOIN race ra ON re.raceid = ra.id
GROUP BY d.id, d.name
) a
INNER JOIN
(
SELECT aa.driverid, aa.bestRound, bb.date
FROM result aa
INNER JOIN race bb ON aa.raceid = bb.id
) b ON a.id = b.driverid AND a.bestRound = b.bestRound
INNER JOIN
(
SELECT aa.driverid, aa.bestAverageRound, bb.date
FROM result aa
INNER JOIN race bb ON aa.raceid = bb.id
) c ON a.id = c.driverid AND a.bestAverageRound = c.bestAverageRound
ORDER BY
a.name