Question

PHP lists this example as a way to retrieve database data.

<?php
$return = []
$qry = "SELECT * FROM exp_member_data";
$res = mysql_query($mem_qry);

function mysql_fetch_all($res) {
   while($row=mysql_fetch_array($res)) {
       $return[] = $row;
   }
   return $return;
}
?>

I am confused about how this while loop progresses. What guarantees that $row=mysql_fetch_array($res) is different for every iteration of the while loop?

Answer 1

From the docs:

… moves the internal data pointer ahead.

So it doesn’t guarantee that it will be different, only that it will retrieve the next row.