Removing global from function - php

Question

I've VERY NEW to PDO. I created the below function, but I read having the global database ($dbo) is a bad idea. The code works and outputs what I want it too. Any suggestions on how to improve/fix?
function langString($lang_id) {
global $dbo;
$lang_result=$dbo->prepare("SELECT lang_string FROM lang WHERE lang_id=:lang_id");
$lang_result->bindParam(":lang_id",$lang_id,PDO::PARAM_INT,3);
if($lang_result->execute()){
$lang_row = $lang_result->fetch(PDO::FETCH_OBJ);
echo "<br><br>$lang_row->lang_string";
}
}
echo langString(3);

Answer 1

Pass the variable as an argument to the function
function langString($lang_id, $dbo) {
$lang_result=$dbo->prepare("SELECT lang_string FROM lang WHERE lang_id=:lang_id");
$lang_result->bindParam(":lang_id",$lang_id,PDO::PARAM_INT,3);
if($lang_result->execute()){
$lang_row = $lang_result->fetch(PDO::FETCH_OBJ);
echo "<br><br>$lang_row->lang_string";
}
}
echo langString(3, $dbo);

Answer 2

The catch with the accepted answer is that you will end up trailing your database round every function as a parameter. This results in longer lists of parameters and as you get more stuff starts to look messy.
An alternative method is to make a Singleton which you can call to get the database connection e.g. Normally large projects will use this for more than just accessing the DB but here's a simple example
class DatabaseProvider {
private static $database;
private $dbo;
private function __construct() {
//Here's where you do your PDO connection creation
$this->dbo= new PDO()....;
}
public static function getDatabase() {
if(!isset(self::$database) {
self::$database = new DatabaseProvider();
}
return $database->dbo;
}
}
Then you just call DatabaseProvider::getInstance() which returns the pdo object

Answer 3

Use an include file...
Put your variables or even create a db object in the include, and then you can call it from anywhere.
function langString($lang_id) {
include($_SERVER['DOCUMENT_ROOT']."/dbconnect.php"); //Put your vars in this document
$lang_result=$dbo->prepare("SELECT lang_string FROM lang WHERE lang_id=:lang_id");
$lang_result->bindParam(":lang_id",$lang_id,PDO::PARAM_INT,3);
if($lang_result->execute()){
$lang_row = $lang_result->fetch(PDO::FETCH_OBJ);
echo "<br><br>$lang_row->lang_string";
}
}
echo langString(3);