PHP - foreach only updates first row - php

Question

I'm trying to update multiple rows using a form and a foreach loop. I've tried solutions found on stackoverflow, but just can't seem to get it to work. I'm working on page project.php?id=13
My HTML form:
<form method="post" action="project.php?id=<?php echo $id; ?>">
<?php while($row = $shops->fetch_assoc()) : ?>
<input type="hidden" name="shop[]" value="<?php echo $row['id']; ?>">
<input type="text" name="boxposition[]" class="form-control" value="<?php echo $row['box_position']; ?>" style="width: 50px;">
<input type="submit" name="update" value="Update Order" class="btn btn-primary">
<?php endwhile; ?>
</form>
My PHP code (on the same page) which is executed on if(isset($_POST['update'])) :
$shopid = $_POST['shop'];
$boxorder = $_POST['boxposition'];
foreach ($shopid as $index => $value) {
$query = "UPDATE shops SET box_position = '".$boxorder[$index]."' WHERE id = '".$shopid[$index]."'";
$update_row = $db->update($query);
Unfortunately, it only updates the first row (lowest id). The very strange thing is that I get the correct values when I echo them using. E.g.:
echo $shopid[$index].'<br>';
echo $boxorder[$index].'<br>';
An example:
I update the $boxorder for 2 rows:
Row 1 (for shop 1): new value = 6 (old value was 7)
Row 2 (for shop 2): new value = 8 (old value was 5)
Using foreach to echo the result, it shows the correct values:
1 (shop id)
6 (new boxorder value)
2 (shop id)
8 (new boxorder value)
What am I missing? Thanks in advance for helping me out!

Answer 1

Try following
<?php while($row = $shops->fetch_assoc()) : ?>
<form method="post" action="project.php?id=<?php echo $id; ?>">
<input type="hidden" name="shop[]" value="<?php echo $row['id']; ?>">
<input type="text" name="boxposition[]" class="form-control" value="<?php echo $row['box_position']; ?>" style="width: 50px;">
<input type="submit" name="update" value="Update Order" class="btn btn-primary">
</form>
<?php endwhile; ?>
to
<form method="post" action="project.php?id=<?php echo $id; ?>">
<?php while($row = $shops->fetch_assoc()) : ?>
<input type="hidden" name="shop[]" value="<?php echo $row['id']; ?>">
<input type="text" name="boxposition[]" class="form-control" value="<?php echo $row['box_position']; ?>" style="width: 50px;">
<input type="submit" name="update" value="Update Order" class="btn btn-primary">
<?php endwhile; ?>
</form>

Answer 2

$shopid = $_POST['shop'];
$boxorder = $_POST['boxposition'];
$query = "UPDATE shops SET box_position =? WHERE id =?";
$db->prepare($query);
foreach ($shopid as $index => $value) {
$db->execute(array($boxorder[$index], $shopid[$index]));
}
This should do it. This way you prepare the statement with ? and fill it inside your for each.
you can do it with also as the following :
$query = "UPDATE shops SET box_position = :position WHERE id = :id ";
$db->prepare($query);
foreach ($shopid as $index => $value) {
$db->execute(
array(
':position' => $boxorder[$index],
':id' => $shopid[$index]
)
);
}