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.
Related
I have a list of data contians (yyyy-mm-dd, hh:min:ss) from this data i need to sort out how many times 'logins' was punched for any given hour of the day. and also how many times logins' was punched for each day of the week .
I tried some code but am not confident the code i have right. Also should i include COUNT(*) in the statement
This code for hourly logins :
SELECT date_time, HOUR(date_time) FROM time_logs ORDER BY DAY(date_time);
Code for day for week:
SELECT date_time, DAY(date_time) FROM time_logs ORDER BY DAY(date_time);
Is this is right. If not could you give me hint
To count how many logins per hour, you just need to add COUNT(*) in your SELECT and GROUP BY HOUR(date_time).
SELECT date_time, HOUR(date_time),COUNT(*) 'Total Logins'
FROM time_logs GROUP BY HOUR(date_time) ORDER BY DAY(date_time);
Similarly on your day count you need to add the same thing. Only difference is your grouping is now by day.
SELECT date_time, DAY(date_time), COUNT(*) 'Total Logins'
FROM time_logs GROUP BY DAY(date_time) ORDER BY DAY(date_time);
You can cast your datetime to both hour and date and then group by to get your aggregations.
https://rextester.com/BQSV80644
For hour of the day:
SELECT HOUR(date_time), COUNT(*)
FROM time_logs
GROUP BY HOUR(date_time);
For day of the week:
SELECT WEEKDAY(date_time), COUNT(*)
FROM time_logs
GROUP BY WEEKDAY(date_time)
ORDER BY MIN(date_time)
So I have a query which will count how many records there are for each date in the past 3 days, from my last question with the help of others I was able to come up with the following:
SELECT COUNT(*) AS dailyCount
FROM highscores
WHERE DATE(date) BETWEEN CURDATE() - INTERVAL 3 DAY AND CURDATE()
GROUP BY DATE(date)
The query does the following, for the past 30 days, it will get how many records there are on each individual day and that will be returned as dailyCount.
However what I want to do now is get it so that dailyCount will only count fields where username has not been counted before.
I have tried the following (adding username to the GROUP BYs):
SELECT COUNT(*) AS dailyCount
FROM highscores
WHERE DATE(date) BETWEEN CURDATE() - INTERVAL 3 DAY AND CURDATE()
GROUP BY DATE(date), username
However that did not give the expected result.
Credits to Wrikken
The following worked:
SELECT COUNT(DISTINCT username) AS dailyCount
FROM highscores
WHERE DATE(date) BETWEEN CURDATE() - INTERVAL 3 DAY AND CURDATE()
GROUP BY DATE(date)
I am trying to count time stamps between two databases but one has overlapping time stamps, due to not my design flaw.
SELECT date(time + INTERVAL 8 HOUR) as day, COUNT(DISTINCT comment)
FROM news.data
GROUP BY day
UNION ALL
SELECT date(time + INTERVAL 8 HOUR) as day, COUNT(DISTINCT comment)
FROM`news-backup`.`data`
GROUP BY day
ORDER BY year(day) desc, day(day) DESC
LIMIT 20
What seems to happen, there are some timestamps in range of both databases so they produce separate counts for certain dates. So it would give count for TODAY from news and news-backup
EX:
date count
2013-1-15 10
2013-1-15 13
2013-1-14 8
2013-1-13 15
What I want is
EX:
date count
2013-1-15 23
2013-1-14 8
2013-1-13 15
Here is a kicker, I need it in a view, so there are some limitations with that (no subqueries allowed). Thoughts? And no I cannot change the data dump sequence that happens between to DBs
You can't put a subquery in a view, but you can put a view in a view.
So:
create view1 as
SELECT date(time + INTERVAL 8 HOUR) as day, 'current' as which, COUNT(DISTINCT comment) as cnt
FROM news.data
GROUP BY day
UNION ALL
SELECT date(time + INTERVAL 8 HOUR) as day, 'backup' as which, COUNT(DISTINCT comment) as cnt
FROM`news-backup`.`data`
GROUP BY day, which
I'm not sure what you logic for combining them is:
create view2 as
select day, max(cnt) -- sum(cnt)? prefer current or backup?
from view1
group by day
ORDER BY day desc
The documentation that bans subqueries is here. Be sure to search for "The SELECT statement cannot contain".
If you have a table of all the dates, the following "absurd" SQL might work:
select c.date,
coalesce( (select count(distinct comment) from news.data where date(time + INTERVAL 8 HOUR) = c.date),
(select count(distinct comment) from news_backup.data where date(time + INTERVAL 8 HOUR) = c.date)
) as NumComments
from calendar c
This version is assuming you want the "new" first, then the backup. If you want the sum, then you would add them.
I have a CHANGES table with fields VALUE(integer) and CREATED_AT(timestamp). I want to know the total of the VALUE column grouped by each of the past 30 days (without making 30 queries).
So if yesterday there were records created with VALUEs of 10, -7, and 12; I would want a record returned with CREATED_AT = yesterday and TOTAL = 15.
Any help?
SELECT date(created_at) as CREATED_AT, sum(value) as TOTAL
FROM changes
WHERE created_at >= curdate() - interval 30 day
GROUP BY date(created_at);
Well, it slightly depends on what kind the timestamp is formatted in (SQL/ Unix/ etc). But this type of query might help you along:
SELECT
DATE_FORMAT(CREATED_AT, '%Y-%m-%d') ym,
COUNT(VALUE)
FROM foo
GROUP BY ym
Suppose you have a table of the form:
create table user_activity (
user_id int not null,
activity_date timestamp not null,
...);
It's easy enough to select the number of unique user_id's in the past 30 days.
select count(distinct user_id) from user_activity where activity_date > now() - interval 30 day;
But how can you select the number of unique user_ids in the prior 30 days for each of the past 30 days? E.g. uniques for 0-30 days ago, 1-31 days ago, 2-32 days ago and so on to 30-60 days ago.
The database engine is mysql if it matters
You could try using a sub query:
SELECT DISTINCT `activity_date` as `day`, (
SELECT count(DISTINCT `user_id`) FROM `user_activity` WHERE `activity_date` = `day`
) as `num_uniques`
FROM `user_activity`
WHERE `activity_date` > NOW() - INTERVAL 30 day;
This should give you the number of unique users for each day. However, I haven't tested this since I don't have the DB to work with.
I haven't tried this in MySQL, but hopefully the syntax is right. If not, maybe it will point you in the right direction. First, I often employ a Numbers table. It can be a physical table simply made up of numbers or it can be a generated/virtual/temporary table.
SELECT
N.number,
COUNT(DISTINCT UA.user_id)
FROM
Numbers N
INNER JOIN User_Activity UA ON
UA.activity_date > NOW() - INTERVAL 30 + N.number DAY AND
UA.activity_date <= NOW() - INTERVAL N.number DAY
WHERE
N.number BETWEEN 0 AND 30
GROUP BY
N.number
I'm not familiar with the whole INTERVAL syntax, so if I got that wrong, please let me know and I'll try to correct it.
If you get the days number for todays date and mod it by 30 you get the offset of the current day. Then you add that to each number for a date and divide the result by 30, this gives you the group of days. Then group your results by this number. So in code something like this:
select count(distinct user_id), (to_days(activity_date)+(to_days(now()) % 30)) / 30 as period
from user_activity
group by (to_days(activity_date)+(to_days(now()) % 30)) / 30
I will leave calculating the reverse numbering of period up to you (hint: take the period number for the current date as "max" and subtract period above and add 1.)