PHP基于另一个数组的键创建一个数组

Question

Background: I have an array created by:

$order  = $_POST['order'];

The contents only have a single value per row:

[0] => 1
[1] => 4
[2] => 5
[3] => 2
[4] => 2

I am updating a database with this:

for ($i=0; $i<count($order); $i++)
{
$sql = "UPDATE catalog SET quantity=quantity - $order[$i]  WHERE item_number= $i +1";

$result = mysqli_query($connection,$sql) or
die("<b>Query Failed.</b><br>" . mysqli_error($connection));
}

But I would like to use SELECT to search for records in which I have updated. Of course the problem is I do not have a direct item number to reference since I used $i +1 to refer to it.

As you can see the (array)key+1 to each value is equal to the item_number. So I was hoping to create an array in which the following is true:

for ($i=0; $i<count($order); $i++)
{ 
if ($order[$i] > 0)
{
$itemNum[$i] = 1;
} else {
$itemNum[$i] = 0;
}

I am sure I am over thinking this but I just need to be able to set up a WHERE statement displaying only item_num records which were just updated.

Answer 1

Make an array containing all the item_numbers you are updating. Then, select those item_numbers.

$updated = [];
for ($i=0; $i<count($order); $i++)
{
  if ($order[$i] > 0) {
    $updated[] = $i + 1;
    $sql = "UPDATE catalog SET quantity=quantity - $order[$i]  WHERE item_number= $i +1";
    $result = mysqli_query($connection,$sql) or
       die("<b>Query Failed.</b><br>" . mysqli_error($connection));
  }
}
$sql = "SELECT * FROM catalog WHERE item_number IN (" . implode(",", $updated) . ")";

What are you going to do if the order is for more quantity than are remaining in catalog?