Consider the following table which has the fields - id (int) and date_created (datetime):
id date_created
1 2010-02-25 12:25:32
2 2010-02-26 13:40:37
3 2010-03-01 12:02:22
4 2010-03-01 12:10:23
5 2010-03-02 10:10:09
6 2010-03-03 12:45:03
I want to know the busiest/most popular hour of the day for this set of data. In this example, the result I'm looking for would be 12.
Ideas?
To get just the most popular hour, use this query
select date_format( date_created, '%H' ) as `hour`
from [Table]
group by date_format( date_created, '%H' )
order by count(*) desc
limit 1;
If you want to look at all the data, go with this one
select count(*) as num_records
, date_created
, date_format( date_created, '%H' ) as `hour`
from [Table]
group by `hour`
order by num_records desc;
If you want something a little more flexible, perhaps to the half hour, or quarter hour, you can do the following:
SELECT floor(time_to_sec(date_created)/3600),count(*) AS period
FROM table GROUP BY period ORDER BY c DESC
If you want the most popular 2 hour interval, use 7200. The most popular 15 minute interval, use 900. You just need to remember you are dealing with seconds (3600 seconds in an hour).
Use the hour() function to extract the hour, then do the usual aggregation:
SELECT count(hour(date_created)) AS c, hour(date_created) AS h FROM table GROUP BY h ORDER BY c DESC;
I like both Simon and Peter's answers, but I can't select both as accepted. I combined the 2 to make a cleaner query that only returned the popular hour (I don't need the counts).
SELECT hour(date_created) AS h
FROM my_table
GROUP BY h
ORDER BY count(*) DESC
LIMIT 1
You could try this:
SELECT
DATE_FORMAT(date,'%H') as hours,
count(*) as count
FROM
myTable
GROUP BY
hours
ORDER BY
count DESC
Related
I am trying to figure out how to sort by time hourly with the following dataset.
hm,total_count,avg_count,max_count
-------------------------------------
'23:15','17','5.6667','9'
'23:45','19','3.1667','5'
'06:15','13','6.5000','9'
'05:15','22','4.4000','7'
'05:45','12','6.0000','11'
'04:15','22','4.4000','6'
'04:45','14','4.6667','7'
'03:45','24','2.4000','5'
'02:45','82','5.4667','13'
'01:45','98','6.1250','13'
'00:45','59','4.2143','11'
My query:
SELECT DATE_FORMAT(`dt`, '%H:%i') as hm, SUM(`counts`) AS total_count,
AVG(`counts`) AS avg_count, MAX(`counts`) AS max_count
FROM pax_load_distribution , plans
WHERE `pax_load_distribution`.`plan_id` = `plans`.`id` AND
`plans`.`dt` BETWEEN '2017-05-01' AND '2017-05-31'
GROUP BY hm
ORDER BY HOUR(hm) DESC, MINUTE(hm) ASC;
But as you can see, the query organize the 23 hours on top but not in a sequence from 23,00,01,02 etc. How can I make it such that the 23 hours are on top follow by 00,01 etc.
Try to use HOUR(dt + INTERVAL 1 HOUR) instead of HOUR(hm) DESC in your ORDER BY clause.
You can try : ORDER BY (HUOUR(hm) * 60 + MINUTE(hm)) ASC
Imagine a table with field 'datetime'. Example rows:
2017-01-27 13:06:02
2017-01-27 05:13:14
2017-01-23 22:13:56
2017-01-26 14:02:09
2017-01-23 13:26:12
...
I need to get * from the bold lines, BUT WITHIN the last 30 days from now...
In other words, rows with the max date in the last 30 days.
30 rows in total in each case, assuming every day has at least one row...
You can group by the date part of datetime and get the max for each day.
select max(`datetime`)
from tablename
where `datetime` >= date(now())-interval '30' day
group by date(`datetime`)
To get all the fields from the table for such rows, use
select * from tablename where `datetime` in (
select max(`datetime`)
from tablename
where `datetime` >= date(now())-interval '30' day
group by date(`datetime`)
)
vkp's answer is basically correct, although there's no need for subquery to select the final result from - you can just put other columns straight into your query, up to something like this:
select *, max(datetime)
from tablename
where datetime >= date(now())-interval '30' day
group by date(datetime);
Ah, and that works for joins too.
The other thing I'd change to address the goal more precise, is:
max(time(datetime))
select * from your_table
where datetime between sysdate and sysdate-30
I am collecting data every five minutes and entering it into a MySQL database. I would like to extract the most recent row that's over 2 hours old, followed by over 1 hour old, followed by the most recent row.
I was thinking something along the lines of the following, but I think this will get me the last row of each hour. Meaning if I run the query at 8:05 I might get back rows from 6:57, 7:57 and 8:02, the last 2 of which are much less than an hour apart.
SELECT *
FROM (
SELECT *
FROM mytable
ORDER BY Date DESC
GROUP BY HOUR(Date) LIMIT 3
) x
ORDER BY Date ASC
Thanks for any help or suggestions you can provide.
SELECT * FROM (
SELECT * FROM mytable
WHERE `Date`<DATE_SUB(NOW(), INTERVAL 2 HOUR)
ORDER BY DATE DESC LIMIT 1
)
UNION
SELECT * FROM (
SELECT * FROM mytable
WHERE `Date`<DATE_SUB(NOW(), INTERVAL 1 HOUR)
ORDER BY DATE DESC LIMIT 1
)
UNION
SELECT * FROM (
SELECT * FROM mytable
ORDER BY DATE DESC LIMIT 1
)
ORDER BY `Date`ASC
I have a number of posts saved into a InnoDB table on MySQL. The table has the columns "id", "date", "user", "content". I wanted to make some statistic graphs, so I ended up using the following query to get the amount of posts per hour of yesterday:
SELECT HOUR(FROM_UNIXTIME(`date`)) AS `hour`, COUNT(date) from fb_posts
WHERE DATE(FROM_UNIXTIME(`date`)) = CURDATE() - INTERVAL 1 DAY GROUP BY hour
This outputs the following data:
I can edit this query to get any day I want. But what I want now is the AVERAGE of each hour of every day, so that if on Day 1 at 00 hours I have 20 posts and on Day 2 at 00 hours I have 40, I want the output to be "30". I'd like to be able to pick date periods as well if it's possible.
Thanks in advance!
You can use a sub-query to group the data by day/hour, then take the average by hour across the sub-query.
Here's an example to give you the average count by hour for the past 7 days:
select the_hour,avg(the_count)
from
(
select date(from_unixtime(`date`)) as the_day,
hour(from_unixtime(`date`)) as the_hour,
count(*) as the_count
from fb_posts
where `date` >= unix_timestamp(current_date() - interval 7 day)
and created_on < unix_timestamp(current_date())
group by the_day,the_hour
) s
group by the_hour
Aggregate the information by date and hour, and then take the average by hour:
select hour, avg(numposts)
from (SELECT date(`date`) as day, HOUR(FROM_UNIXTIME(`date`)) AS `hour`,
count(*) as numposts
from fb_posts
WHERE DATE(FROM_UNIXTIME(`date`)) between <date1> and <date2>
GROUP BY date(`date`), hour
) d
group by hour
order by 1
By the way, I prefer including the explicit order by, since most databases do not order the results of a group by. Mysql happens to be one database that does.
SELECT
HOUR(FROM_UNIXTIME(`date`)) AS `hour`
, COUNT(`id`) \ COUNT(DISTINCT TO_DAYS(`date`)) AS avgHourlyPostCount
FROM fb_posts
WHERE `date` > '2012-01-01' -- your optional date criteria
GROUP BY hour
This gives you a count of all the posts, divided by the number of days, by hour.
Lets say I have a table of messages that users have sent, each with a timestamp.
I want to make a query that will tell me (historically) the most number of messages a user ever sent in an hour.
So in other words, in any given 1 hour period, what was the most number of messages sent.
Any ideas?
Assuming timestamp to be a DATETIME - otherwise, use FROM_UNIXTIME to convert to a DATETIME...
For a [rolling] count within the last hour:
SELECT COUNT(*) AS cnt
FROM MESSAGES m
WHERE m.timestamp BETWEEN DATE_SUB(NOW(), INTERVAL 1 HOUR)
AND NOW()
GROUP BY m.user
ORDER BY cnt DESC
LIMIT 1
If you want a specific hour, specify the hour:
SELECT COUNT(*) AS cnt
FROM MESSAGES m
WHERE m.timestamp BETWEEN '2011-06-06 14:00:00'
AND '2011-06-06 15:00:00'
GROUP BY m.user
ORDER BY cnt DESC
LIMIT 1
Need more details on table structure etc. but something like:
select date(timestmp), hour(timestmp) , count(*)
from yourtable group by date(timestmp) , hour(timestmp)
order by count(*) DESC
limit 100;
would give you hte desired result.
Something like this should work:
SELECT MAX(PerHr) FROM
(SELECT COUNT(*) AS PerHr FROM messages WHERE msg_uid=?
GROUP BY msg_time/3600) t
I suspect this would be horribly slow, but for an arbitrary historical max hour, something like this might work (downvote me if I'm way off, I'm not a MySQL person):
SELECT base.user, base.time, COUNT(later.time)
FROM messages base
INNER JOIN messages later ON later.time BETWEEN base.time AND DATE_ADD(base.time, INTERVAL 1 HOUR) AND base.user = later.user
WHERE base.user = --{This query will only work for one user}
GROUP BY base.user, base.time
ORDER BY COUNT(later.time) DESC
LIMIT 1