PHP Filter html select option value if it is found in the database

Question

I have a database where plots (spots/places) are saved (this can be 5, 40 ,91 etc. (not incremented)) On my website I have a dropdown option where available plots are selected (0 - 1023). I want the option that is found in the database to be hidden from the dropdown selection on the website. So if plot 1 is taken it is found in the database and it shouldn't be available in the website dropdown selection. I can't seem to get this working...

This is the code that I came up with.

<label for="plotnumber">Plotnumber :</label></br>
<select name="input_plotnumber">

<?php for ($i = 0; $i <= 1023; $i++) : ?>

$query = ("SELECT plotnumber FROM plot1");
$result = $conn->query($query);
$arrayofplots = mysqli_fetch_all($result);

if (in_array($i, $arrayofplots)) {

}
else {
<option value="<?php echo $i; ?>"><?php echo $i; ?></option>
}

<?php endfor; ?>?>
</select>

Answer 1

If you modify the SQL to select all taken plots you can then decide to only output option elements whose value is not within that recordset. Based upon your comment that there is a column taken you might try like this:

<label>Plotnumber :

    <br />

    <?php
        $sql='select plotnumber from plot1 where taken=1';
        $res=$conn->query($sql);
        $data=$res->fetch_all(MYSQLI_ASSOC);
    ?>


    <select name="input_plotnumber">
        <option selected disabled hidden>Select Plot
        <?php
            for( $i=0; $i < 1024; $i++ ){
                if( !in_array( $i, array_column($data,'plotnumber') ) )printf('<option>%d',$i);
            }
        ?>
    </select>

</label>

Answer 2

• You need to convert the two-dimensional array returned by mysqli_fetch_all into a one-dimensional array before you can use in_array .
• As you have some column to indicate if the plot is taken, you need to put that in a WHERE clause. I have used taken=1 but if you have a string like taken/not taken then modify it accordingly.
• Avoid running a query in a loop. Instead you should fetch the data at the top.
• As a rule of thumb, choose either the object oriented style $result->fetch_all() or procedural mysqi_fetch_all() , instead of mixing both.

Updated code:

<?php

$query = "SELECT plotnumber FROM plot1 WHERE taken=1";
$result = $conn->query($query);
$arrayofplots = $result->fetch_all();

// convert to a 1d array
$arrayofplots = array_map(function($row){
  return $row[0];
}, $arrayofplots);

?>

<label for="plotnumber">Plotnumber :</label></br>
<select name="input_plotnumber">

<?php
for ($i = 0; $i <= 1023; $i++){
  if (!in_array($i, $arrayofplots)) {
    echo '<option value="' . $i . '">' . $i . '</option>';
  }
}
?>

</select>