Retrieve a selection of drop down list in php - php

Question

I retrieved the selection of drop down from database. Now, I want to edit the entries. When I open the page for edit, I should have the selected data of drop down displayed in the page.
I used the following code to populate the drop down list.
<?php
try {
$sql1 = "select vehicleno from vehicle";
$projresult = $dbh->query($sql1);
$projresult->setFetchMode(PDO::FETCH_ASSOC);
} catch (PDOException $e) {
die("Some problem getting data from database !!!" . $e->getMessage());
}
echo '<select name="vehicleno" id="vehicleno" class="form-control" required value="<?php echo htmlentities($result->vehicleno);?>>';
$vno=$_POST['vehicleno'];
while ( $row = $projresult->fetch() ) {
echo '<option value="'.$row['vehicleno'].'">'.$row['vehicleno'].'</option>';
}
echo '</select>';
?>

Answer 1

You can't set the value of a select box directly in html, therefore as you loop through the options you'd have to check if that is the option selected. For example...
echo '<select name="vehicleno" id="vehicleno" class="form-control" required';
$vno = $_POST['vehicleno'];
while ( $row = $projresult->fetch() ) {
echo '<option value="' . $row['vehicleno'] . '"' . ($vno == $row['vehicleno'] ? 'selected' : '') . '>'.$row['vehicleno'].'</option>';
}
echo '</select>';
If this was your parent page and you wanted to send the value to a subpage such as edit-vehicle.php then you'd have to use a form element...
echo '<form action="edit-vehicle.php" method="post"><select name="vehicleno" id="vehicleno" class="form-control" required';
$vno = $_POST['vehicleno'];
while ( $row = $projresult->fetch() ) {
echo '<option value="' . $row['vehicleno'] . '"' . ($vno == $row['vehicleno'] ? 'selected' : '') . '>'.$row['vehicleno'].'</option>';
}
echo '</select></form>';
See https://www.w3schools.com/php/php_forms.asp for more about php form handling.