Question

I have 2 dates. Lets say they look like this.

$start = 2010/12/24;
$end = 2012/01/05;

I query the database to look for visits between these two dates. I find some. I then populate an array called stats.

$stats['2010/12/25'] = 50;
$stats['2010/12/31'] = 25;
...

As you can see, there are days missing. I need to fill the missing dates with a value of zero. I was thinking something like this. (I have pulled day / month / year from start and end dates.

for($y=$start_year; $y <= $end_year; $y++) {
    for($m=$start_month; $m <=$end_month; $m++) {
        for($d=$start_day; $d <= $end_day; $d++) {

This would work fine for the year however the months and days wouldn’t work. If the start day is the 15th. Days 1-14 of each subsequent month would be missed. I could have a solution like this then…

for($y=$start_year; $y <= $end_year; $y++) {
    for($m=1; $m <13; $m++) {
         $total_days = cal_days_in_month(CAL_GREGORIAN, $m, $y) + 1;
         for($d=1; $d <= $total_days; $d++) {

I would then need a bunch of if statements making sure starting and end months and days are valid.

Is there a better way of doing this? Or could this even be done in my mysql query?

Answer 1

Just to demonstrate the power of some of PHP’s newer interval handling method (mentioned by pgl in his answer):

$startDate = DateTime::createFromFormat("Y/m/d","2010/12/24",new DateTimeZone("Europe/London"));
$endDate = DateTime::createFromFormat("Y/m/d","2012/01/05",new DateTimeZone("Europe/London"));

$periodInterval = new DateInterval( "P1D" ); // 1-day, though can be more sophisticated rule
$period = new DatePeriod( $startDate, $periodInterval, $endDate );

foreach($period as $date){
   echo $date->format("Y-m-d") , PHP_EOL;
}

Does require PHP >= 5.3.0

EDIT

If you need to include the actual end date, then you need to add a day to $endDate immediately before the foreach() loop:

$endDate->add( $periodInterval );

EDIT #2

$startDate = new DateTime("2010/12/24",new DateTimeZone("Europe/London"));
$endDate = new DateTime("2012/01/05",new DateTimeZone("Europe/London"));

do {
   echo $startDate->format("Y-m-d") , PHP_EOL;
   $startDate->modify("+1 day");
} while ($startDate <= $endDate);

For PHP 5.2.0 (or earlier if dateTime objects are enabled)