Repeat insert query with a different date given by a frequency - php

Question

I'm building a system where an user can register activities. However the activities registered can repeat over the course of the year.
In order to prevent having the need that the user has to fill in the form to create an activity multiple times for each different date, I had the idea to add a textbox and a dropdown to the form to allow the user to fill in a frequency. The user can fill in a number in the textbox (for example "2") and select a value from the dropdown (for example "week"). So from that selection the activity has to be added to the database for the next 2 weeks on the same day.
However I have no idea how to let PHP adjust the date and add exactly 7 days to the selected date and repeat the same insert query with the new date, for every week/month/year selected from the given frequency.
EDIT 1:
I've tried this so far:
while ($i> 0)
{
$query2 = $this->db->connection->prepare("INSERT INTO activity(Act_Startdate) values (?)");
$query2->bind_param("s", $Startdate);
$query2->execute();
$Dates = date('d-m-Y', strtotime($Startdate . '+ 1 days'));
$Startdate = date('d-m-Y', strtotime($Dates));
$i--;
}
The first date insertion works, but the second one results 0000-00-00.

Answer 1

Read more about :
Date Time in PHP.
Date Interval in PHP
$numberPostedByUser = $_POST['your_input_name_in_form'];
$currentDate = new \DateTime(); // Getting current date
$iterator = 1;
while ($iterator <= $numberPostedByUser) {
$currentDate->add(new \DateInterval('P1D')); // Adding interval of one day in current date
$startDate = $currentDate->format('Y-m-d H:i:s'); // converting that day in convenient format we required
$query2 = $this->db->connection->prepare("INSERT INTO activity(Act_Startdate) values (?)");
$query2->bind_param("s", $startDate);
$query2->execute();
$iterator++; // increasing iterator for next loop
}
Hope may this code will help you.