Recommendation script not working when trying to combine both components - php

Question

Context
I am building a simple recommendation script that serves to provide a user with the next upcoming date for a particular day of the week that he/she has booked the most.
(i.e. JohnDoe's most popular day to book is a Thursday, and the date of the next Thursday to come up is 2019/03/07)
This is what I am dealing with :
<?php
$date = new DateTime();
$date->modify('next thursday');
echo $date->format('Y-m-d');
?>
<?php require "snippets/get_booking_recommended_day.php" ?>
The first PHP code returns the next upcoming date for whatever day is asked. It works as it should. The PHP require references code from another folder that returns the users most popular day, in String format. (eg Monday, Tuesday). It also works.
My issue comes when trying to get the first bit of code to understand what is being returned from the 2nd bit of code.
I've attempted the following...
<?php
$date = new DateTime();
$date->modify('next' require "snippets/get_booking_recommended_day.php");
echo $date->format('Y-m-d');
?>
I've tried every variation possible. Nothing seems to work.
I'm quite new to PHP, and im 90% sure my coding practice is terrible but I am trying my best to grasp it - but so far this simple issue is beyond me.
Please help.
APPENDICES
Filename: snippets/get_booking_recommended_day.php
(Return the most booked day of the last 3 months by the user currently in session)
<?php
if ($mysqli->connect_errno) {
echo "Failed to connect to MySQL: (" . $mysqli->connect_errno . ") " . $mysqli->connect_error;
}
// Asks the qry: Of the last 90 days, what is the most booked day of the week for the current member in session?
// Min date is CURRENT_DATE() -100 instead of CURRENT_DATE() -30, because the MySQL function CURRENT_DATE() prints the date in an int format (YYYYMMDD) with no date formatting. Thus, to get the date a month ago, we must subtract this int by 100 so as to remove 1 from the 6th number in the series of numbers. Which is the 2nd M number.
$sql = "SELECT DATE_FORMAT(tbl_booking.booking_date, '%W'), COUNT(DATE_FORMAT(tbl_booking.booking_date, '%W')) AS mostpopularday
FROM tbl_booking
WHERE tbl_booking.member_ID=$_SESSION[member_ID]
AND tbl_booking.booking_date <= CURRENT_DATE()
AND tbl_booking.booking_date >= CURRENT_DATE() -300
GROUP BY DATE_FORMAT(tbl_booking.booking_date, '%W')
ORDER BY mostpopularday DESC
LIMIT 1";
$result = $mysqli->query($sql);
if ($result->num_rows > 0) {
// output data of each row
while($row = $result->fetch_assoc()) {
echo $row["DATE_FORMAT(tbl_booking.booking_date, '%W')"];
}
} else {
// Return Nothing.
}
?>
Filename : pagebooking.php
(This is the datepicker that is located inside my pagebooking.php, its purpose is to choose the day of a booking. My hope is to populate this field with the recommended date that will be generated from the 2 PHP scripts above.).
<input name="new_booking_date" width="276" placeholder="Date" class="form-control input-md" type="date" max="<?php echo date("Y-m-d", strtotime("+30 day")); ?>" min="<?php echo date("Y-m-d", strtotime("+1 day")); ?>" required="" />

Answer 1

Issue resolved.
<?php
// If there are any values in the table, display them one at a time.
if ($mysqli->connect_errno) {
echo "Failed to connect to MySQL: (" . $mysqli->connect_errno . ") " . $mysqli->connect_error;
}
// Asks the qry: Of the last 90 days, what is the most booked day of the week for the current member in session?
// Min date is CURRENT_DATE() -100 instead of CURRENT_DATE() -30, because the MySQL function CURRENT_DATE() prints the date in an int format (YYYYMMDD) with no date formatting. Thus, to get the date a month ago, we must subtract this int by 100 so as to remove 1 from the 6th number in the series of numbers. Which is the 2nd M number.
$sql = "SELECT DATE_FORMAT(tbl_booking.booking_date, '%W'), COUNT(DATE_FORMAT(tbl_booking.booking_date, '%W')) AS mostpopularday
FROM tbl_booking
WHERE tbl_booking.member_ID=$_SESSION[member_ID]
AND tbl_booking.booking_date <= CURRENT_DATE()
AND tbl_booking.booking_date >= CURRENT_DATE() -300
GROUP BY DATE_FORMAT(tbl_booking.booking_date, '%W')
ORDER BY mostpopularday DESC
LIMIT 1";
$result = $mysqli->query($sql);
if ($result->num_rows > 0) {
// output data of each row
while($row = $result->fetch_assoc()) {
$recommended_day = $row["DATE_FORMAT(tbl_booking.booking_date, '%W')"];
$date = new DateTime();
$date->modify('next '.$recommended_day);
echo $date->format('Y-m-d');
}
} else {
}
?>