insert query mysql throws PDO::exec() expects exactly 1 parameter, 2 given - php

Question

I've pieced together some code I've gleaned from the internet: I'm trying to scan a directory to insert file names and index into MariaDB table. My last hurdle it seems is this PDO error: PDO::exec() expects exactly 1 parameter, 2 given on line 55. I've tagged line(55) with '//error thrown here'.
My novice guess is it doesn't like the parameters escaped in []??
As noted above novice here...
Any insight/help is greatly appreciated. Thanks in advance.
<?php
$host = 'localhost';
$dbname = 'dirdb';
$username = 'root';
$password = '';
// Create connection
try {
$conn = new PDO("mysql:host=$host;dbname=$dbname", $username, $password);
// set the PDO error mode to exception
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
echo "Connected successfully";
} catch(PDOException $e) {
echo "Connection failed: " . $e->getMessage();
}
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);
$dir = './recipes';
$GLOBALS['I'] = 0; // root folder given index 0
function dirToArray( $dir , $parent) {
$result = array();
$cdir = scandir($dir);
foreach ($cdir as $key => $value) {
if (!in_array($value, array(".", ".."))) {
if (is_dir($dir . DIRECTORY_SEPARATOR . $value)){
$result[$value] = [++$GLOBALS['I']]; // add folder index
$result[$value][] = $parent; // add parent folder index
$result[$value][] = dirToArray($dir . DIRECTORY_SEPARATOR . $value, $GLOBALS['I']);
} else {
$result[] = $value;
}
}
}
return $result;
}
$res = dirToArray($dir, $GLOBALS['I']);
function dirToDb($res, $parentId = 0)
{global $conn;
foreach ($res as $key => $value) {
if (is_array($value)) {
$conn->exec ("insert into sp_files (path, parentId) VALUES (?, ?)", [$key, $parentId]); //error thrown here
dirToDb($value, $conn->fetch("SELECT LAST_INSERT_ID()"));
} else {
$conn->exec ("insert into sp_files (path, parentId) VALUES (?, ?)", [$value, $parentId]);
}
}
}
//$res = dirToArray($dir);
dirToDb($res);

Answer 1

You can't use $conn->exec() to execute a query with parameters. You have to use prepare() to create a statement, then execute the prepared statement.
There's also no $conn->fetch() method. fetch() is a method of the PDOStatement class, you can use it either with a prepared statement or the result of a query. But you don't need to perform a query to get LAST_INSERT_ID(), PDO has an insertId() method for this.
function dirToDb($res, $parentId = 0) {
global $conn;
$stmt = $conn->prepare("insert into sp_files (path, parentId) VALUES (?, ?)");
foreach ($res as $key => $value) {
$stmt->execute([$key, $parentId]);
if (is_array($value)) {
dirToDb($value, $stmt->insertId);
}
}
}