PHP PDO error undefined index serial - php

Question

I'm about to pull my hair out. I can't get the undefined index to go away. Basically where it says echo htmlspecialchars($r['serial']) I want it to list the item out of the database table.
<?php
try{
$conn = new PDO("mysql:host=$sql_server;dbname=$sql_db", $sql_user, $sql_pass);
$sql = "SELECT serial, model, deviceCondition, sealCondition, location, deployDate, weight, notes FROM $sql_table ORDER BY serial";
$q = $conn->prepare($sql);
$q->setFetchMode(PDO::FETCH_OBJ);
while ($r = $q->fetch());
} catch (PDOEException $pe) {
die("Could not connect to the database" . $pe->getMessage());
}
?>
</div>
<?php
$r = $q->fetchAll();
echo htmlspecialchars($r['serial'])
?>

Answer 1

You are referring to the result as an associative array where you expect to have the key 'serial'. This is the behavior of PDO::FETCH_NAMED, not PDO::FETCH_OBJ. Just use the right fetch mode, and you should be fine:
$q->setFetchMode(PDO::FETCH_NAMED);

Answer 2

see the below code, the fetchAll will get the results in an associative array, so you can get the data like $row['serial'] and use it later.
also added the execute() on the pdo statement obj.
<?php
try{
$conn = new PDO("mysql:host=$sql_server;dbname=$sql_db", $sql_user, $sql_pass);
$sql = "SELECT serial, model, deviceCondition, sealCondition, location, deployDate, weight, notes FROM $sql_table ORDER BY serial";
$q = $conn->prepare($sql);
$q->execute(); // make sure to add this
$results = $q->fetchAll();
foreach($results as $row) {
echo htmlspecialchars($row['serial']) . "<br>";
//if you want to use the serial later, just store it into an array
$serials [] = htmlspecialchars($row['serial']);
}
// while ($r = $q->fetch()); this is not needed because of the fetchAll statement above
}
catch (PDOEException $pe) {
die("Could not connect to the database" . $pe->getMessage());
}
?>
</div>
<?php
//$r = $q->fetchAll(); not needed here, we did it above already
?>
<?php
//echo htmlspecialchars($r['serial']); use your array from above
print_r($serials);
?>
let me know if it helps