Why does this code only show 1 ID

Question

I am having a problem. I know I am using deprecated MySQL, but I am working on a website for school and security is not necessary(as long as it works). I am trying to get all the Id's from a table called Reviews. This should be stored in a array. For some reason it only shows the first one. How to get all of them stored in 1 array? This is my code which is not working:

$sql1 = "SELECT Klanten_id FROM Reviews";
$res1 = mysql_query($sql1);
$r = mysql_fetch_assoc($res1)['Klanten_id'];

Answer 1

1.Don't use outdated mysql_* library.Turn to mysqli_* or PDO.

2.mysql_fetch_assoc: Fetch a result row as an associative array. So you need to apply loop to get all data

Like below:-

$ids = array(); //created an array
while ($row = mysql_fetch_assoc($res1)) {
    $ids[] = $row['Klanten_id']; // assign each id to the array
}
print_r($ids);// print array

3.To start working on mysqli/PDO check basic example here:- mysqli/PDO example