PHP strtotime'本月第一天'没有返回第一天

Question

I'm currently using the script below to report back the events start and end date over the period of one month, hence using 'first day of this month' and 'last day of this month'

I've no idea why but any events that start on the first of March have note been included, any help as to why would be great. Thanks

 <?php
    global $wpdb;
    $result = $wpdb->get_results ( "

        SELECT

        $wpdb->posts.post_title,
        substring_index(GROUP_CONCAT(meta_value order by str_to_date(meta_value,'%Y-%m-%d %H:%i:%s')), ',', 1) as start_date,
        substring_index(GROUP_CONCAT(meta_value order by str_to_date(meta_value,'%Y-%m-%d %H:%i:%s')), ',', -1) as end_date

        FROM $wpdb->posts INNER JOIN $wpdb->postmeta

        ON $wpdb->posts.id = $wpdb->postmeta.post_id

        WHERE $wpdb->postmeta.meta_key='_EventStartDate' OR $wpdb->postmeta.meta_key='_EventEndDate'

        GROUP BY $wpdb->postmeta.post_id

        ORDER BY $wpdb->postmeta.meta_value

        " );

    foreach ( $result as $page ) {

        $date1 = new DateTime($page->start_date);
        $date2 = new DateTime($page->end_date);

        if (strtotime($page->start_date) >= strtotime('first day of this month') && strtotime($page->start_date) < strtotime('last day of this month')) {

            echo '<h2><div class="date-title">';
            echo $page->post_title;
            echo '</div><div class="date-date">';
            echo  '<span class="orderby">Order by ' . $date1->format('d-m-y') . '</span><span class="deliveryby"> For Delivery ' . $date2->format('d-m-y').'</span><br/>'; 
            echo '</div></h2>';
        }
    }     
?>

Answer 1

strtotime() uses the components of the current time for components it cannot find in the input string.

You don't specify a time of day in "first day or this month", that's why strtotime() returns the correct date but with the current time:

echo(date('r', strtotime('first day of this month')));
# Wed, 01 Mar 2017 13:50:08 +0000

You can compare your page times (>=) against

strtotime('first day of this month midnight')

and (<):

strtotime('first day of next month midnight')

to get the correct results.

echo(date("r", strtotime("last day of this month midnight")));
# Fri, 31 Mar 2017 00:00:00 +0000
echo(date("r", strtotime("first day of next month midnight")));
# Sat, 01 Apr 2017 00:00:00 +0000

If you also need to consider the timezone, I recommend you to avoid the old date&time PHP functions (they do not handle the timezone) and use the DateTime class instead:

$timezone = new DateTimeZone('Europe/Bucharest');
$startMonth = new DateTime('first day of this month midnight', $timezone);
$endMonth   = new DateTime('first day of next month midnight', $timezone);

$startPage = new DateTime($page->start_date, $timezone);
$endPage   = new DateTime($page->end_date, $timezone);

if ($startMonth <= $startPage && $startPage < $endMonth) {
    // ...
}