How to Round a DateTime Down to the Nearest Quarter Hour in PHP?

Round Minute Down to Nearest Quarter Hour in PHP

To round the time stored in a MySQL 'datetime' column down to the nearest quarter hour, we can leverage the 'floor()' function.

$sql = "SELECT datetime_column FROM table_name";
$result = mysqli_query($conn, $sql);

while ($row = mysqli_fetch_assoc($result)) {
    $timestamp = strtotime($row['datetime_column']);
    $rounded_time = floor($timestamp / (15 * 60)) * (15 * 60);

    // Convert the rounded timestamp back to a time string
    $rounded_time_string = date('H:i', $rounded_time);
}

In this example:

• The 'floor()' function is used to round the timestamp down to the nearest quarter.
• The timestamp is divided by "(15 * 60)" to convert it to minutes, then multiplied by the same value to round it back to the nearest quarter.
• Finally, the rounded timestamp is converted back to a time string using 'date()'.

Example:

$timestamp = strtotime('2010-03-18 10:50:00');
$rounded_time = floor($timestamp / (15 * 60)) * (15 * 60);
echo date('H:i', $rounded_time); // Output: 10:45

Note that this approach can also be used to round up to the nearest quarter by replacing 'floor()' with 'ceil()'.

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