Uncaught Error: Call to a member function prepare() (PDO, php) - php

Question

I'm trying to get data from a table using a public function in PHP, but I get this error:
Uncaught Error: Call to a member function prepare() (PDO, php)
I'm searching for 2, 3 hours... But no result is similar or I did not understand.
<?php
class Config {
public static $SQL;
private function __construct() {
$host_name = "localhost";
$base_user = "root";
$base_pass = "";
$base_name = "home_page";
try {
self::$SQL = new PDO("mysql:host=$host_name;dbname=$base_name", $base_user, $base_pass);
self::$SQL->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
echo "Connected successfully";
} catch(PDOException $e) {
die("Something went wrong, database connection closed. Reason: ". $e->getMessage());
}
}
public static function GetData($table, $data, $id) {
$wc = Config::$SQL->prepare('SELECT `'.$data.'` FROM `'.$table.'` WHERE `ID` = ?');
$wc->execute(array($id));
$r_data = $wc->fetch();
return $r_data[$data];
}
}
?>
And I use this in my base file:
<h1><?php echo Config::GetData("page_details", "Moto", 1) ?></h1>
The error is from this line:
$wc = self::$SQL->prepare('SELECT `'.$data.'` FROM `'.$table.'` WHERE `ID` = ?');

Answer 1

Is there any particular reason why you want to use STATICeverywhere? The common approach is using public, dynamic methods and properties. I rewrote your sample with suggested naming convention in PHPs OOP, it works:
<?php
class Config
{
/** #var PDO $conn */
private $conn = null;
public function __construct()
{
$host_name = "localhost";
$base_user = "root";
$base_pass = "";
$base_name = "home_page";
try {
$this->conn = new PDO("mysql:host=$host_name;dbname=$base_name", $base_user, $base_pass);
$this->conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
echo "Connected successfully"; // <- this is unnnesesary
} catch (PDOException $e) {
die("Something went wrong, database connection closed. Reason: " . $e->getMessage());
}
}
public function findById($table, $data, $id)
{
$stmt = $this->conn->prepare('SELECT `' . $data . '` FROM `' . $table . '` WHERE `uid` = ?');
$stmt->execute(array($id));
return $stmt->fetch(PDO::FETCH_ASSOC);
}
}
// just for test
$cfg = new Config();
print_r($cfg->findById('foo', '*', 1));
or in your case
<?php echo $cfg->findById("page_details", "Moto", 1)['Moto'] ?>