Mysql and PHP frequency based on time - php

Question

I am working on a project to graph frequency over a time period. The server currently stores all the data I need apart from the count as this will change over time. I am pulling all of the data that I need using the following code:
<?php
$con = mysql_connect("127.0.0.1",xxx,xxx);
if (!$con) {
die('Could not connect: ' . mysql_error());
}
mysql_select_db("tweets", $con);
$results = array();
$result = mysql_query("SELECT company, time FROM data WHERE company = 'AAPL'");
while($row = mysql_fetch_array($result))
{
$results[] = $row;
}
$results = json_encode($results);
mysql_close($con);
echo $results;
?>
When returned I have an array that contains all of the company names and times. how would I go about counting the frequency within a time frame, for example the frequency in the past 24 hours and then a separate value for the previous 24 hours?

Answer 1

You just loop through the data, the exact code depends on the format of the time and the format of the result required. You could do something like this :
$summary =array();
foreach($results as $result)
{
$day = substring($result['time'], 0, 10);
if(isset($summary[$day])){
$summary[$day]++;
} else {
$summary[$day] = 1;
}
}
Write the function getDay() according to the format of the time.

Answer 2

If your date/time values are stored as MySQL datetime (and for your sake I hope they are) then the solution is trivial. Select records within a certain time period and group by company, e.g.
SELECT
`company`, COUNT(`company`) AS total
FROM
`data`
WHERE
`time` >= now() - INTERVAL 1 DAY
GROUP BY
company
In this example I use MySQL to compute the 24 hour period, but you could just as easily have PHP compute an exact time/date.
If you want a pure PHP solution, then start by storing your times grouped by companies in a multidimensional array. Convert your times from your DB format to Unix time. In my example I use strtotime(); if your db times are in a funky format then you'll need to do something else to convert them.
$result = mysql_query("SELECT company, time FROM data");
while($row = mysql_fetch_array($result)) {
$results[$row['company']] = strtotime($row['time']);
}
Then simply loop the array and evaluate.
// 24 hours before now
$start = time() - ( 24*60*60);
$lastTwentyFourHours = array();
foreach ( $results as $company => $times ) {
if ( !isset($lastTwentyFourHours[$company]) ) {
$lastTwentyFourHours[$company] = 0;
}
foreach ( $times as $time ) {
if ( $time >= $start ) {
$lastTwentyFourHours[$company]++;
}
}
}
print_r($lastTwentyFourHours);