<?php
require_once('includes/connection.php');  // make sure this sets up $conn

if (!empty($_POST['itemName'])) {
    $item = $_POST['itemName'];

    // assuming your item_master has columns 'unit' and 'extra_description'
    $stmt = $conn->prepare("SELECT `unit`, `description`  FROM `item_master`  WHERE `item_name` = ? LIMIT 1");
    $stmt->bind_param('s', $item);
    $stmt->execute();
    $stmt->bind_result($unit, $extraDesc);

    if ($stmt->fetch()) {
        echo json_encode([
            'unit'              => $unit,
            'extra_description' => $extraDesc
        ]);
    } else {
        echo json_encode([
            'unit'              => '',
            'extra_description' => ''
        ]);
    }
    $stmt->close();
}