PHP For Loop, Matching Outputs With Database Results - php

Question

I feel like I'm missing something easy here and getting a little stuck while building a "schedule an appointment" calendar.
Clients can book their own time slots, and when they do...I need to make those time slots unavailable to others.
I am using a drop down to "for loop" in 30 minute intervals from 9am - 7pm for the "start time" selection. If a "start time" of "10:00am" and an "end time" of "11:30am" are saved in the database...10:00am, 10:30am, and 11:00am need to be withheld from the "start time" dropdown after successful form submission.
(Database results are in the form of a string...fyi)
To do that, I have this:
$sql_slots = "SELECT * FROM XXXXXXXXX WHERE date = '$query_date' ORDER BY XXXXXXXXX ASC";
$result_slots = mysqli_query($connection, $sql_slots);
$open = strtotime("9:00am");
echo'
<select name="start_time">';
for($b = 0; $b <= 20; $b++){
$y = strtotime(($b*30) . " Minutes", $open);
$the_time = date("h:ia", $y) . "<br>";
$starting = array();
while($row_result_slots = mysqli_fetch_assoc($result_slots)){
$starting[] = $row_result_slots['start_time'];
}
if(in_array($the_time, $starting)){
echo "<option>Not Available</option>";
} else {
echo "<option>" . $the_time . "</option>";
}
}
echo'</select>';
Any suggestions, to finish this or a better method than "in_array" to accomplish what I'm trying to do?
Thank you in advance.

Answer 1

The solution was to move the "while loop" outside of the "for loop" and I wasn't taking into account the "br" attached to the end of the $the_time variable.
Here is the working code:
$sql_slots = "SELECT * FROM XXXXXX WHERE date = '$query_date' ORDER BY XXXXXXX ASC";
$result_slots = mysqli_query($connection, $sql_slots);
$open = strtotime("9:00am");
$starting = array();
while($row_result_slots = mysqli_fetch_assoc($result_slots)){
$starting[] = $row_result_slots['start_time'];
}
echo'
<select name="start_time">';
for($b = 0; $b <= 20; $b++){
$y = strtotime(($b*30) . " Minutes", $open);
$the_time = date("h:ia", $y);
if(in_array($the_time, $starting)){
echo "<option>Not Available<br></option>";
} else {
echo "<option>" . $the_time . "<br></option>";
}
}