Bulk MySQL update instead of PHP While loop - php

Question

I am using PHP code to update week ending date which is on a different day for each subdomain. Each subdomain date range varies.
My current code uses a while loop to update the week end date. This is very slow and I am looking for ideas to optimise it.
Here is my current code:
// Loop through and assign week end date to each user activity.
$nextWeek = $startDate; // initialise while loop condition
while ($nextWeek <= $endDate) {
$lastWeek = $nextWeek;
$nextWeek = Carbon::parse($lastWeek)->addWeek(1)->format('Y-m-d');
// update activity date to week end date
$query = 'UPDATE r_active_user_activities
SET week_end_date = "' . $nextWeek . '"
WHERE (activity_date > "' . $lastWeek . '"
AND activity_date <= "' . $nextWeek . '"
AND subdomain="' . $subdomain->subdomain . '" );';
$db->statement($query);
}

Answer 1

Just append all those update queries in a php variable ($query) and execute that outside the while loop. something like this.
$nextWeek = $startDate; // initialise while loop condition
$query = '';
while ($nextWeek <= $endDate) {
$lastWeek = $nextWeek;
$nextWeek = Carbon::parse($lastWeek)->addWeek(1)->format('Y-m-d');
// update activity date to week end date
$query .= 'UPDATE r_active_user_activities
SET week_end_date = "' . $nextWeek . '"
WHERE (activity_date > "' . $lastWeek . '"
AND activity_date <= "' . $nextWeek . '"
AND subdomain="' . $subdomain->subdomain . '" );';
}
$db->statement($query);