MYSQL NOT IN Query not working unless hard coded - php

Question

I'm fairly new to Javascript and PHP so I have no idea what I'm doing for the most part. I'm trying to make a Room Booking System.
$booking_id = '';
if(isset($_POST['edit_button_booking'])){
$booking_id = $_POST['edit_id'];
}
echo "<script>alert('$booking_id')</script>";
$today_date = date('Y-m-d');
$room_query = "SELECT * FROM rooms";
$room_run = $conn->query($room_query);
if($room_run->num_rows>0){
$options = mysqli_fetch_all($room_run, MYSQLI_ASSOC);
}
$start_from = 8;
$end_from = 21;
$start_to = $start_from+1;
$end_to = $end_from+1;
$from_booked = [];
$to_booked = [];
if(isset($_POST['value'])){
$room_id = $_POST['value'];
$specify_query = "SELECT * FROM rooms WHERE room_id = '$room_id'";
$specify_run = $conn->query($specify_query);
$row = mysqli_fetch_assoc($specify_run);
$room_name = $row['room_name'];
$disable_query = "SELECT booking_id, room_id, booking_date, booking_start, booking_end FROM booking WHERE booking_date = '$today_date' AND room_id = '$room_id' AND booking_id NOT IN (SELECT booking_id FROM booking WHERE booking_id = '$booking_id')";
$disable = $conn->query($disable_query);
if($disable->num_rows > 0){
while($row = $disable->fetch_assoc()){
$from_booked_hour = date_parse($row['booking_start'])['hour'];
$to_booked_hour = date_parse($row['booking_end'])['hour'];
$from_booked = array_merge($from_booked, range($from_booked_hour, $to_booked_hour-1));
$to_booked = array_merge($to_booked, range($from_booked_hour+1, $to_booked_hour));
}
}
}
This is my code. What this code is supposed to do is to display the booked time slots for the room except for the chosen time slot.
And yet, it keeps on displaying both booked times when I want the 9 -12 time slot to be omitted from the time table
The alert that I used show that $booking_id has the value '000053' which is the id of the booking that I want not shown in the time table.
If I were to hard code it to $booking_id = '000053' or $booking_id = 53, it works.
$booking_id = '';
if(isset($_POST['edit_button_booking'])){
$booking_id = $_POST['edit_id'];
}
$booking_id = 53;
echo "<script>alert('$booking_id')</script>";
$today_date = date('Y-m-d');
$room_query = "SELECT * FROM rooms";
$room_run = $conn->query($room_query);
if($room_run->num_rows>0){
$options = mysqli_fetch_all($room_run, MYSQLI_ASSOC);
}
$start_from = 8;
$end_from = 21;
$start_to = $start_from+1;
$end_to = $end_from+1;
$from_booked = [];
$to_booked = [];
if(isset($_POST['value'])){
$room_id = $_POST['value'];
$specify_query = "SELECT * FROM rooms WHERE room_id = '$room_id'";
$specify_run = $conn->query($specify_query);
$row = mysqli_fetch_assoc($specify_run);
$room_name = $row['room_name'];
$disable_query = "SELECT booking_id, room_id, booking_date, booking_start, booking_end FROM booking WHERE booking_date = '$today_date' AND room_id = '$room_id' AND booking_id NOT IN (SELECT booking_id FROM booking WHERE booking_id = '$booking_id')";
$disable = $conn->query($disable_query);
if($disable->num_rows > 0){
while($row = $disable->fetch_assoc()){
$from_booked_hour = date_parse($row['booking_start'])['hour'];
$to_booked_hour = date_parse($row['booking_end'])['hour'];
$from_booked = array_merge($from_booked, range($from_booked_hour, $to_booked_hour-1));
$to_booked = array_merge($to_booked, range($from_booked_hour+1, $to_booked_hour));
}
}
}
I don't know what is causing this issue. Any help will be appreciated.
The var_dump of both queries are as follows:
Generated SQL:
string(156) "SELECT booking_id, room_id, booking_date, booking_start, booking_end FROM booking WHERE booking_date = '2022-07-22' AND room_id = '1' AND booking_id != '53'"
Hard Coded:
string(156) "SELECT booking_id, room_id, booking_date, booking_start, booking_end FROM booking WHERE booking_date = '2022-07-22' AND room_id = '1' AND booking_id != '53'"
UPDATE:
The var_dump()'s I posted earlier were outside of the if(isset($_POST['value'])) block since I thought the variable $booking_id can be accessed in the if block as well. I tried to use var_dump() inside the if block and it turned out that the $booking_id was turning up blank.
string(154) "SELECT booking_id, room_id, booking_date, booking_start, booking_end FROM booking WHERE booking_date = '2022-07-22' AND room_id = '1' AND booking_id != ''"
This was the result of the var_dump() running inside of the if block. I don't understand why it is doing this though. My $today_date variable was defined outside of the if block as well and that's working.