This is my scenario: I have a table that contains events, every event has a field called 'created' with the timestamp in which that event was created. Now I need to sort the events from newest to oldest, but I do not want MySQL to return them all. I need only the latest in a given interval, for example in a range of 24 hours (EDIT: I'd like to have a flexible solution, not only for a 24 hours range, but maybe every few hours). And I only need for the last 10 days. I have achieved that but i'm sure in the most inefficient ways possible, that is, something like that:
$timestamp = time();
for($i = 0; $i < 10; $i++) {
$query = "SELECT * FROM `eventos` WHERE ... AND `created` < '{$timestamp}' ORDER BY `created` DESC LIMIT 1";
$return = $database->query( $query );
if($database->num( $return ) > 0) {
$event = $database->fetch( $return );
$events[] = $event;
$timestamp = $timestamp - 86400;
}
}
I hope I was clear enough. Thanks,
Jesús.
If you have an index with created as the leading column, MySQL may be able to do a reverse scan. If you have a 24 hour period that doesn't have any events, you could be returning a row that is NOT from that period. To make sure you're getting a row in that period, you would really need to include a lower bound on the created column as well, something like this:
SELECT * FROM `eventos`
WHERE ...
AND `created` < FROM_UNIXTIME( {$timestamp} )
AND `created` >= DATE_ADD(FROM_UNIXTIME( {$timestamp} ),INTERVAL -24 HOUR)
ORDER BY `created` DESC
LIMIT 1
I think the big key to performance here is an index with created as the leading column, along with all (or most) of the other columns referenced in the WHERE clause, and making sure that index is used by your query.
If you need a different time interval, down to the second, this approach could be easily generalized.
SELECT * FROM `eventos`
WHERE ...
AND `created` < DATE_ADD(FROM_UNIXTIME({$timestamp}),INTERVAL 0*{$nsecs} SECOND)
AND `created` >= DATE_ADD(FROM_UNIXTIME({$timestamp}),INTERVAL -1*{$nsecs} SECOND)
ORDER BY `created` DESC
LIMIT 1
From your code, it looks like the 24-hour periods are bounded at an arbitrary time... if the time function returns e.g. 1341580800 ('2012-07-06 13:20'), then your ten periods would all be from 13:20 on a given day to 13:20 the following day.
(NOTE: be sure that if your parameter is a unix timestamp integer, that this is being interpreted correctly by the database.)
It might be more efficient to pull the ten rows in a single query. If there is a guarantee that 'timestamp' is unique, then it's possible to craft such a query, but the query text will be considerably more complex than what you have now. We could mess with getting MAX(timestamp_) within each period, and then joining that back to get the row... but that's going to be really messy.
If I were going to try to pull all ten rows I would probably try going with a UNION ALL approach, not very pretty, but it least it could be tuned.
SELECT p0.*
FROM ( SELECT * FROM `eventos` WHERE ...
AND `created` < DATE_ADD(FROM_UNIXTIME({$timestamp}),INTERVAL 0*24 HOUR)
AND `created` >= DATE_ADD(FROM_UNIXTIME({$timestamp}),INTERVAL -1*24 HOUR)
ORDER BY `created` DESC LIMIT 1
) p0
UNION ALL
SELECT p1.*
FROM ( SELECT * FROM `eventos` WHERE ...
AND `created` < DATE_ADD(FROM_UNIXTIME({$timestamp}),INTERVAL -1*24 HOUR)
AND `created` >= DATE_ADD(FROM_UNIXTIME({$timestamp}),INTERVAL -2*24 HOUR)
ORDER BY `created` DESC LIMIT 1
) p1
UNION ALL
SELECT p2.*
FROM ( SELECT * FROM `eventos` WHERE ...
AND `created` < DATE_ADD(FROM_UNIXTIME({$timestamp}),INTERVAL -2*24 HOUR)
AND `created` >= DATE_ADD(FROM_UNIXTIME({$timestamp}),INTERVAL -3*24 HOUR)
ORDER BY `created` DESC LIMIT 1
) p2
UNION ALL
SELECT p3.*
FROM ...
Again, this could be generalized, to pass in a number of seconds as an argument. Replace HOUR with SECOND, and replace the '24' with a bind parameter that has a number of seconds.
It's rather long winded, but it should run okay.
Another really messy and complicated way to get this back in a single result set would be to use an inline view to get the end timestamp for the ten periods, something like this:
SELECT p.period_end
FROM (SELECT DATE_ADD(t.t_,INTERVAL -1 * i.i_* {$nsecs} SECOND) AS period_end
FROM (SELECT FROM_UNIXTIME( {$timestamp} ) AS t_) t
JOIN (SELECT 0 AS i_
UNION ALL SELECT 1
UNION ALL SELECT 2
UNION ALL SELECT 3
UNION ALL SELECT 4
UNION ALL SELECT 5
UNION ALL SELECT 6
UNION ALL SELECT 7
UNION ALL SELECT 8
UNION ALL SELECT 9
) i
) p
And then join that to your table ...
ON `created` < p.period_end
AND `created` >= DATE_ADD(p.period_end,INTERVAL -1 * {$nsecs} SECOND)
And pull back MAX(created) for each period GROUP BY p.period_end, wrap that in an inline view.
And then join that back to your table to get each row.
But that is really, really messy, hard to understand, and not likely to be any faster (or more efficient) than what you are already doing. The most improvement you could make is the time it takes to run 9 of your queries.
Assuming you want the latest (having the greatest created date) event per day for the last 10 days.
so let's get the latest timestamp per day
$today = date('Y-m-d');
$tenDaysAgo = date('Y-m-d', strtotime('-10 day'));
$innerSql = "SELECT date_format(created, '%Y-%m-%d') day, MAX(created) max_created FROM eventos WHERE date_format(created, '%Y-%m-%d') BETWEEN '$today' and '$tenDaysAgo' GROUP BY date_format(created, '%Y-%m-%d')";
Then we can select all the events that match those created dates
$outerSql = "SELECT * FROM eventos INNER JOIN ($innerSql) as A WHERE eventos.created = A.max_created";
I haven't had a chance to test this, but the principles should be sound enough.
If you want to group by some other arbitrary number of hours you would change innerSql:
$fromDate = '2012-07-06' // or if you want a specific time '2012-07-06 12:00:00'
$intervalInHours = 5;
$numberOfIntervals = 10;
$innerSql = "SELECT FLOOR(TIMESTAMPDIFF(HOUR, created, '$fromDate') / $intervalInHours) as grouping, MAX(created) as max_created FROM eventos WHERE created BETWEEN DATE_SUB('$fromDate', INTERVAL ($intervalInHours * $numberOfIntervals) HOUR) AND '$fromDate' GROUP BY FLOOR(TIMESTAMPDIFF(HOUR, created, '$fromDate') / $intervalInHours)";
I'd add another column that is the date(not time) and then use MySQL "group by" to get the most recent for each date.
http://www.tizag.com/mysqlTutorial/mysqlgroupby.php/
This tutorial does just that, but by product type instead of date. This should help!
Do you want all of the events within the 10 days, or just one event per day within the 10 day period?
Either way, consider MySQL's date functions for assistance. It should help you get the date range you want.
Here's one that will get you the first event of the day for the last 10 days.
SELECT *
FROM eventos
WHERE created BETWEEN DATE_SUB(DATE(NOW()), INTERVAL 10 DAY) AND DATE_ADD(DATE(NOW()), INTERVAL 1 DAY)
GROUP BY DATE(created)
ORDER BY MAX(created) DESC
LIMIT 10
Try this:
SELECT *
FROM eventos
WHERE created BETWEEN DATE_SUB(DATE(NOW()), INTERVAL 10 DAY) AND DATE_ADD(DATE(NOW()), INTERVAL 1 DAY)
ORDER BY created DESC
LIMIT 10
Related
Im trying to make a count of the lasts IDs created in the day and the lasts in the month using this code
$TodayAttacks = $odb->query("SELECT COUNT(id) FROM `logs`
WHERE `date` BETWEEN DATE_SUB(CURDATE(), INTERVAL '-1' DAY) AND
UNIX_TIMESTAMP()")->fetchColumn(0);
$MonthAttack = $odb->query("SELECT COUNT(id) FROM `logs`
WHERE `date` BETWEEN DATE_SUB(CURDATE(), INTERVAL '-30' DAY) AND
UNIX_TIMESTAMP()")->fetchColumn(0);
I put it on the html like always but later foto
It shows 0 and thats incorrect. The things that work good is to show the total and running ids.
$RunningAttacks = $odb->query("SELECT COUNT(*) FROM `logs` WHERE `time` + `date` > UNIX_TIMESTAMP() AND `stopped` = 0")->fetchColumn(0);
$TotalAttacks = $odb->query("SELECT COUNT(*) FROM `logs`")->fetchColumn(0);
Both of this things work but the other ones to calculate in a day and in a month dont works, just it shows 0.
Here is how the IDs on the MySQL works
foto
I need help to fix the $TodayAttacks and $MonthAttack to calculate what they need to.
If someone knows how to fix this tell me :)
Since you're using the DATE_SUB function you won't need negative numbers for your interval value. To get the running count from yesterday until now:
$TodayAttacks = $odb->query("SELECT COUNT(id) FROM `logs`
WHERE `date` > UNIX_TIMESTAMP(DATE_SUB(CURDATE(), INTERVAL 1 DAY))")->fetchColumn(0);
To get the count for the last 30 days, try:
$MonthAttack = $odb->query("SELECT COUNT(id) FROM `logs`
WHERE `date` > UNIX_TIMESTAMP(DATE_SUB(CURDATE(), INTERVAL 30 DAY))")->fetchColumn(0);
An example of how this works is posted here:
https://www.db-fiddle.com/f/itLtCzJbPbWuCWcx3jLiMk/1
I am trying to select 3 random records from a MySQL db where the lastUsedDate (the date the record was last updated) is beyond a set time period or NULL.
My logic is this:
If the lastUsedDate is NULL, then this record could be selected.
If the lastUsedDate is 7 days or more older than the current date,
it is a candidate to be randomly selected.
I want to ignore dates that are 7 days and younger.
I know Rand() is slow, but this table only has 30 records.
SELECT * FROM myTable
WHERE lastUsedDate <= DATE_SUB(CURDATE() ,INTERVAL 7 DAY) OR lastUsedDate IS NULL
ORDER BY RAND()
LIMIT 3
Eventually, after 30 days, the lastUsedDate will no longer be NULL as all 30 will be used up. This is why I want to recycle rows after 7 days.
Anyone point me in the right direction?
Try
SELECT * FROM myTable
WHERE IFNULL(lastUsedDate, '0000-00-00') <= DATE_SUB(CURDATE() ,INTERVAL 7 DAY)
ORDER BY RAND()
LIMIT 3
Since you tagged this as PHP I'm guessing you are running this query inside PHP, in which case why not simplify the query and do more in php
$date_limit = date("Y-m-d", strtotime("-7 days", time()));
$sql = "SELECT * FROM myTable WHERE IFNULL(lastUsedDate, '0000-00-00') <= '$date_limit' ORDER BY RAND() LIMIT 3";
good luck
Hi all i currently have this sql:
SELECT a.*
FROM (SELECT a.*
FROM articles a
WHERE date >= UNIX_TIMESTAMP(DATE(NOW() - INTERVAL 7 DAY)) AND a.active = 1
ORDER BY views ASC
) a
ORDER BY views ASC
It lists all articles posted in the last week, what I want to do is adjust it so it ignored today, is that easy to do?
Certainly. You just need to add AND date < UNIX_TIMESTAMP(CURDATE())
For simplicity, you can use the BETWEEN operator:
WHERE `date` BETWEEN UNIX_TIMESTAMP(DATE(NOW() - INTERVAL 7 DAY))
AND UNIX_TIMESTAMP(DATE(NOW() - INTERVAL 1 DAY))
I believe this allows the engine to make better use of indexes than individual >= and <= calls, but I'm not certain on that.
Shouldn't
SELECT `a`.*
FROM `articles` AS a
WHERE `date` >= UNIX_TIMESTAMP(NOW(TODAY() - INTERVAL 7 DAY)) AND `date` <= UNIXTIMESTAMP(DATE(NOW() - INTERVAL 1 DAY)) `a`.`active` = 1
ORDER BY `views` ASC
Suffice for this task?
Im having a little trouble constructing a query.
I have a table with 3 columns.
id - day - pageviews
What i basically want to do is get 8 id's from the table where the pageviews are the highest from the last 60 days.
The day column is a datetime mysql type.
Any help would be great, im having a little trouble figuring this one out.
Cheers,
Almost the same as TuteC posted, but you'll need a group by to get what you need...
SELECT id, SUM(pageviews) totalViews
FROM table
WHERE DATE_SUB(CURDATE(), INTERVAL 60 DAY) <= day
GROUP BY id
ORDER BY totalViews DESC
LIMIT 8
Do something like this:
SELECT id FROM table_name
WHERE DATE_SUB(CURDATE(),INTERVAL 60 DAY) <= day
ORDER BY pageviews DESC
LIMIT 8;
$sixtyDaysAgo = date('Y-m-d',strtotime('-60 days'));
$sql = "SELECT id
FROM table_name
WHERE day >= '$sixtyDaysAgo 00:00:00'
ORDER BY pageviews DESC
LIMIT 8";
If each row is a number of pageviews for that day, and you're looking for the highest total sum of 60 days' worth, then you'll need to total them all and then grab the top 8 from among those totals, like so:
$sql = "SELECT id
FROM (
SELECT id, SUM(pageviews) AS total_pageviews
FROM table_name
WHERE day >= '$sixtyDaysAgo 00:00:00'
GROUP BY id
) AS subselect
ORDER BY total_pageviews DESC
LIMIT 8";
I'm trying to create a custom query that will show the number of stories that have been posted in the last 24 hours on a Drupal 6 site.
Stories are stored in the "node" table. each record has a "created" row that records the UNIX timestamp when the story was posted.
Here's the query I'm trying so far:
$sq = 'SELECT COUNT(*) cnt '
. 'FROM {node} c WHERE created >= dateadd(hour,-24,getdate())';
This doesn't appear to be working though. What am I doing wrong?
EDIT: Here's the overall code I'm trying to use right now:
$sq = 'SELECT COUNT(*) AS cnt FROM {NODE} n WHERE FROM_UNIXTIME(n.created) >= DATE_SUB(NOW(), INTERVAL 1 DAY)';
$q = db_query($sq);
while ($o = db_fetch_object($q)) {
print_r($o);
}
That print_r isn't returning anything. Where's my error?
For MySQL, use:
SELECT COUNT(*) AS cnt
FROM NODE n
WHERE FROM_UNIXTIME(n.created) >= DATE_SUB(NOW(), INTERVAL 1 DAY)
Mind that NOW() includes the time when the statement is run. If you want to count records, starting from midnight of the previous day, use:
SELECT COUNT(*) AS cnt
FROM NODE n
WHERE FROM_UNIXTIME(n.created) >= DATE_SUB(CURRENT_DATE, INTERVAL 1 DAY)
Reference:
FROM_UNIXTIME
DATE_SUB
Since you are doing this in PHP, you can just use $_SERVER['REQUEST_TIME']. My guess is that it will be faster than doing date manipulations with SQL:
$count = db_result(db_query("SELECT COUNT(nid) FROM {node}
WHERE created >= %d;", $_SERVER['REQUEST_TIME'] - 86400));
Alternative you could use time to get the current timestamp, but that will be a tiny bit slower than using the $_SERVER['REQUEST_TIME'] variable.