How do I dynamically define an index using an existing select query? - php

Question

I am trying to use IsNull() to return the current variable value, but I receive an undefined Index error. The issue is that the query returns a full array.
How do I go about assigning a specific memberID so IsNull() will return the information already in the DB back into the query, thus stopping the query from erasing my current field data.
if(!empty($_POST)) {
switch (true) {
//Removed other case for brevity
case isset($_POST['update']):
if($_POST['name'] != "") {
$name = trim($_POST['name']);
}
else {
$name = NULL;
}
if($_POST['designation'] != "") {
$designation = trim($_POST['designation']);
}
else {
$designation = NULL;
}
if($_POST['rank'] != "") {
$rank = trim($_POST['rank']);
}
else {
$rank = NULL;
}
if($_POST['currentScore'] != "") {
$currentScore = trim($_POST['currentScore']);
}
else {
$currentScore = NULL;
}
if(!is_null($name) || !is_null($designation) || !is_null($rank) || !is_null($currentScore)) {
$update = $conn->prepare("UPDATE members SET name = IsNull(?, name), designation = IsNull(?, designation), rank = IsNull(?, rank), currentScore = IsNull(?, currentScore) WHERE memberID = ? ");//Prepared statements are immune to sql injection, so they are used for security
$update->bind_param('ssiii', $name, $designation, $rank, $currentScore, $memberID);// Binding the values to use in the prepared statement
if($update->execute()) {
header('location: index.php');
die();
}
}
break;
// case isset($_POST['delete']):
// // Delete statement goes here
// break;
}
}
if($results = $conn->query("SELECT *, ((previousScore + currentScore) / 2) AS avgScore FROM members")) {
FROM members")) {
if($results->num_rows) {
while($row = $results->fetch_object()) {
$records[] = $row; //Appending value to array
}
$results->free();
}
}