比较同一行中的两个值并根据需要进行更改

Question

Im trying to compare two values in the same record and if $minvoorraad > $voorraad , set $voorraad = $minvooraad.

Database(cropped picture):

This is what i have now but it changes all numbers to same

<?php
session_start();
include 'connect.php';

$sql = "SELECT Minvoorraad, Voorraad FROM product";
$query = mysqli_query($con, $sql);
if($query === false)
{
  die(mysql_error());

}
else
{

while($row = mysqli_fetch_array($query))
{

if($row['Minvoorraad'] > $row['Voorraad'])
{
    $minvoorraad = $row['Minvoorraad'];
    $sql = "UPDATE Product SET Voorraad = '$minvoorraad'";
    $query = mysqli_query($con, $sql);
}

}
 Header("Location: ../producten.php");


 ?>

By the way im a beginner

Answer 1

Below query will work, unless you need to do query optimization and reduce the locking period

UPDATE Product 
SET Voorraad = Minvoorraad
WHERE Minvoorraad > Voorraad