如果记录存在从菜单选择 html 更改背景颜色

Question

need for clarification. I need a little script that checks if an item in my select menu exists in my table, and the script should look something like this

     <?php 

 $result = mysqli_query($cn, "SELECT ora_inizio, data FROM prenotazioni WHERE ora_inizio = '$hour' and data = '$date' ");
$num_rows = mysqli_num_rows($result);

if ($num_rows > 0) {
 echo " exist";
}
else {
  // do something else
}

?>

My menu select is:

        <option value="9:00">9:00</option>
        <option value="9:15">9:15</option>
        <option value="9:30">9:30</option>
        <option value="9:45">9:45</option>
        <option value="10:00">10:00</option>
        <option value="10:15">10:15</option>
        <option value="10:30">10:30</option>
        <option value="10:45">10:45</option>
        <option value="11:00">11:00</option>

Now I need that if the element exists, it is colored red in the select menu.

So if record (9:00) exist on my table color value 9:00 on select menu.

Answer 1

Maybe you could do something like this. Although it might not be the cleanest approach:

if ($num_rows['ora_inizio'] == '9:00') {
    echo '<option value="9:00" style="color:#e11313">9:00</option>';
}else{
    echo '<option value="9:00">9:00</option>';
}

Answer 2

You need to prepare variable with hours:

$hours = ['9:00', '9:15', '9:30', '9:45', '10:00', '10:15', '10:30', '10:45', '11:00'];

Then You can dynamically create options like this:

foreach($hours as $h) {
    echo '<option value="'.$h.'"'.(($hour == $h and $num_rows) ? ' style="color:#e11313"' : '').'>'.$h.'</option>';
}

Database query may be as You provided. My solution is using your variable $hour and result from query $num_rows .