Save sqldateselect.php as sqldateextract.php.  The page currently displays the dates even though we know all tasks are due within the next day.  It would be more user friendly to extract the day of the week and the time for the task and just display those.

Replace the whole of your middle block of PHP with this similar block (the query has changed and the data in variables):

$sqlResult=mysqli_query($dbconnection, "SELECT DAYNAME(tasktime) AS weekday, HOUR(tasktime) AS hour, 
    MINUTE(tasktime) AS minute, task FROM task WHERE tasktime<=DATE_ADD(NOW(), INTERVAL 1 DAY);");
echo "<p>Tasks:</p>";
echo "<ul>";
while ($sqlRow=mysqli_fetch_array($sqlResult)){
    echo "<li>$weekday {$hour}:{$minute} $task</li>";
echo "</ul>";

Try it.  The strlen() function returns the length of the string and if it is just one character the code adds an extra 0 to the front as normal for minutes and hours.

You can also use: