I have 2 different tables called observations and intervals.
observations:
id | type, | start
------------------------------------
1 | classroom | 2017-06-07 16:18:40
2 | classroom | 2017-06-01 15:12:00
intervals:
+----+----------------+--------+------+---------------------+
| id | observation_id | number | task | time |
+----+----------------+--------+------+---------------------+
| 1 | 1 | 1 | 1 | 07/06/2017 16:18:48 |
| 2 | 1 | 2 | 0 | 07/06/2017 16:18:55 |
| 3 | 1 | 3 | 1 | 07/06/2017 16:19:00 |
| 4 | 2 | 1 | 3 | 01/06/2017 15:12:10 |
| 5 | 2 | 2 | 1 | 01/06/2017 15:12:15 |
+----+----------------+--------+------+---------------------+
I want a view that will display:
observation_id | time_on_task (total time in seconds where task = 1)
1 | 13
2 | 5
So I must first check to see if the first observation has task = 1, if it is I must record the difference between the current interval and the start from the observations table, then add that to the total time. From there on after if the task = 1, I just add the time difference from the current interval and previous interval.
I know I can use:
select observation_id, TIME_TO_SEC(TIMEDIFF(max(time),min(time)))
from your_table
group by observation_id
to find the total time in the intervals table between all intervals outside of the first one.
But
1. I need to only include interval times where task = 1. (The endtime for the interval is the one listed)
2. Need the timediff between the first interval and initial start (from observations table) if number = 1
I'm still new to the Stackoverflow community, but you could try to use SQL
LAG() function
For instance
Using an outer Select Statement
SELECT COl1, COL2, (DATEDIFF(mi, Inner.prevtime, Currentdatetime,0)) AS Difference
FROM ( SELECT LAG(Created_Datetime) OVER (ORDER BY Created_Datetime) AS prevtime
From MyTable
Where SomeCondition) as Inner
Sorry if it looks goofy, still trying to learn to format code here.
https://explainextended.com/2009/03/12/analytic-functions-optimizing-lag-lead-first_value-last_value/
Hope it helps
Related
This question already has an answer here:
Mysql group by two columns and pick the maximum value of third column
(1 answer)
Closed 2 years ago.
I've been taking too long trying to solve this, I need to filter this table:
+----+-------+-------+
| id | jobID |stageID|
+----+-------+-------+
| 1 | 1 | 1 |
| 2 | 1 | 2 |
| 3 | 1 | 2 |
| 4 | 1 | 1 |
| 5 | 2 | 2 |
| 6 | 2 | 1 |
| 7 | 2 | 1 |
| 8 | 2 | 2 |
+----+-------+-------+
You see every job has many rows with different stages, I need to get the last row of every stage of every job.
For example, look at job 1. It has 4 rows, each one with a given stage. I'd need to get the last entry of a stage for that job, which means, rows 3 and 4.
So for the full table I need to get rows No. 3, 4, 7 and 8, like this
+----+-------+-------+
| id | jobID |stageID|
+----+-------+-------+
| 3 | 1 | 2 |
| 4 | 1 | 1 |
| 7 | 2 | 1 |
| 8 | 2 | 2 |
+----+-------+-------+
I think I'll go nuts. I try with GROUP_BY but it groups the stages without taking in count the jobs.
Can you help me?
This is simply:
select max(id) as id, jobID, stageID
from yourtable
group by jobID, stageID
If you need additional information selected, use that as a subselect:
select yourtable.id, yourtable.jobID, yourtable.stageID, yourtable.other
from (
select max(id) as id
from yourtable
group by jobID, stageID
) max_job_stage_ids
join yourtable using (id)
or use IN (I find this less helpful in visualizing the query plan, but some people prefer it):
select id, jobID, stageID, other
from yourtable
where id in (select max(id) from yourtable group by jobID, stageID)
I have two tables i.e vehicle and vehicle_maintenance.
vehicle
-----------------------------------
| v_id | v_name | v_no |
-----------------------------------
| 1 | car1 | car123 |
-----------------------------------
| 2 | car2 | car456 |
-----------------------------------
vehicle_maintenance
-----------------------------------------------------------------------
| v_main_id | v_id | v_main_date | v_main_remainder |
-----------------------------------------------------------------------
| 1 | 1 | 2020/10/10 | 1 |
| 2 | 1 | 2020/10/20 | 2 |
| 3 | 2 | 2020/10/04 | 365 |
| 4 | 2 | 2020/10/15 | 5 |
-----------------------------------------------------------------------
I want to get each car maintenance details i.e car2 maintenance date is 2020/10/15 and i want to check next maintenance date based on v_main_remainder field. That means next maintenance date will be 2020/10/20 ( add 5 day to the maintenance date). I want to also calculate the no of days left from next maintenance date. Suppose today is 2020/10/10 then it will show 10 days left.
Here is my query
SELECT
v.v_id,
v.v_name,
v.v_no,
max(vm.v_main_date) as renewal_date,
datediff(
DATE_ADD(
max(vm.v_main_date), INTERVAL +vm.v_main_remainder day
),
now()
) as day_left
FROM vehicle as v, vehicle_maintenance as vm
GROUP BY v.v_id
But the problem is vm.v_main_remainder in date_add function taken from first row.
Here is the result
-----------------------------------------------------------------------
| v_id | v_name | v_no | renewal_date | day_left |
-----------------------------------------------------------------------
| 1 | car1 | car123 | 2020/10/20 | 11 |
-----------------------------------------------------------------------
| 2 | car2 | car456 | 2020/10/15 | 370 |
-----------------------------------------------------------------------
As a starter, your query is obviously missing a join condition between the two tables, so that's a cartesian product. This type of problem is much easier to spot when using explicit joins.
Then: you want to filter on the latest maintenance record per car, so aggregation is not appropriate.
One option uses window functions, available in MySQL 8.0:
select v.v_id, v.v_name, v.v_no, vm.v_main_date as renewal_date,
datediff(vm.v_main_date + interval vm.v_main_remainder day, current_date) as day_left
from vehicle as v
inner join (
select vm.*, row_number() over(partition by v_id order by v_main_date desc) rn
from vehicle_maintenance
) as vm on vm.v_id = v.v_id
where vm.rn = 1
Note that I changed now() to current_date, so datediff() works consistently on dates rather than datetimes.
I have a MySQL table like this:
acco_id | room_id | arrival | amount | persons | available
1 | 1 | 2015-19-12 | 3 | 4 | 1
1 | 2 | 2015-19-12 | 1 | 10 | 1
1 | 1 | 2015-26-12 | 4 | 4 | 1
1 | 2 | 2015-26-12 | 2 | 10 | 1
2 | 3 | 2015-19-12 | 2 | 6 | 0
2 | 4 | 2015-19-12 | 1 | 4 | 1
What im trying to achieve is a single query with a result like:
acco_id | max_persons_available
1 | 22
2 | 4
I tried using a GROUP BY accommodation_id using a query like:
SELECT
accommodation_id,
SUM(amount * persons) as max_persons_available
FROM
availabilities
WHERE
available = 1
GROUP BY
accommodation_id
Only now the result of acco_id uses all arrival dates. When I add arrival to the query no more unique acco_id's.
Does anyone know a good Single SQL which can use the table indexes?
If I'm understanding the question correct (the last part is a bit confusing). You want to have the accomodation id and numbers as you have now but limited to specific arrival dates.
If so the following statement should do exactly that as it is not necessary to put arrival into the select if you "just" use it in the where statement. As else you would need to put it into the group by and thus have non unique accomodation id's.
SELECT
accommodation_id,
SUM(amount * persons) as max_persons_available
FROM
availabilities
WHERE
available = 1 and arrival >= '2015-12-19' and arrival < '2015-10-26'
GROUP BY
accommodation_id
I guess (reading your question) what you are looking for is this but im not sure as your question is a bit unclear:
SELECT
accommodation_id,
arrival,
SUM(amount * persons) as max_persons_available
FROM
availabilities
WHERE
available = 1
GROUP BY
accommodation_id, arrival
I've got a table which contains week numbers and id's
| id | week |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 8 |
What I need to do is retrieve based on the value of week. But I also need to return the row more than once if the row is greater than a certain number.
For instance (pseudo),
if week > 2
and week > 6
| id | week |
| 2 | 2 |
| 3 | 6 |
| 3 | 6 |
| 4 | 8 |
| 4 | 8 |
ID 3 & ID 4 appear twice, because they're greater than both 2 and 6. ID 2 will only appear once because it is only greater than 2.
Unfortunately looped queries are sort of out of the question as this query will be return 2k+ rows.
Any help will be greatly appreciated, even if the solution is PHP based.
Split the query into multiple queries and then merge the result using UNION.
The following should give you the result you want.
(SELECT * FROM yourTable WHERE week > 2)
UNION ALL
(SELECT * FROM yourTable WHERE week > 6)
edited included the hint by Lily - thx.
I have two MySQL tables: stats (left) and messages (right)
+------------+---------+ +---------+------------+-----------+----------+
| _date | msgcount| | msg_id | _date | time | message |
+------------+---------+ +----------------------+-----------+----------+
| 2011-01-22 | 2 | | 1 | 2011-01-22 | 06:23:11 | foo bar |
| 2011-01-23 | 4 | | 2 | 2011-01-22 | 15:17:03 | baz |
| 2011-01-24 | 0 | | 3 | 2011-01-22 | 17:05:45 | foobar |
| 2011-01-25 | 1 | | 4 | 2011-01-22 | 23:58:13 | barbaz |
+------------+---------+ | 5 | 2011-01-23 | 00:06:32 | foo foo |
| 6 | 2011-01-23 | 13:45:00 | bar foo |
| 7 | 2011-01-25 | 02:22:34 | baz baz |
+---------+------------+-----------+----------+
I filled in stats.msgcount, but in reality it is still empty. I'm looking for a query way to:
count the number of messages for every stats._date (notice the zero msgcount on 2011-01-25)
messages.time is in 24-hour format. All messages AFTER 5 o'clock (17:00:00) should be counted for the next day (notice msg_id 3 and 4 count for 2011-01-23)
update stats.msgcount to hold all counts
I'm especially concerned about the "later than 17:00:00 count for next day" part. Is this possible in (My)SQL?
You could use:
UPDATE stats LEFT JOIN
( SELECT date(addtime(_date,time) + interval 7 hour) as corrected_date,
count(*) as message_count
FROM messages
GROUP BY corrected_date ) mc
ON stats._date = mc.corrected_date
SET stats.msgcount = COALESCE( mc.message_count, 0 )
However this query requires dates you are interested in to be in the stats table already, if you don't have them make _date primary or unique key if its not yet and use:
INSERT IGNORE INTO stats(_date,msgcount)
SELECT date(addtime(_date,time) + interval 7 hour) as corrected_date,
count(*) as message_count
FROM messages
GROUP BY corrected_date
Really, all you're doing is shifting the times by 7 hours. Something like this should work:
UPDATE stats s
SET count = (SELECT COUNT(msg_id) FROM messages m
WHERE m._date BETWEEN DATE_SUB(DATE_ADD(s._date, INTERVAL TIME_TO_SEC(m.time) SECOND), INTERVAL 7 HOUR)
AND DATE_ADD(DATE_ADD(s._date, INTERVAL TIME_TO_SEC(m.time) SECOND), INTERVAL 17 HOUR));
The basic idea is that it takes each date in your stats table, adjusts it by 7 hours, and looks for messages sent in that range. If you used a DATETIME column instead of separate DATE and TIME columns, you wouldn't need the extra DATE_ADD(..., TIME_TO_SEC) stuff.
There may be a better way to add a date and a time, I didn't see one with a quick look at the MySQL reference documents.
So all you'd need to do is insert a new row in the stats table with a 0 for the msgcount, and run the update command. If you only wanted to update a few days (since the message count probably isn't changing 6 days later) you just need a simple where clause on the update:
UPDATE stats s
SET ...
WHERE s._date BETWEEN '2012-04-03' AND '2012-04-08'