Question

Now I am creating a dbo object in each function on my php page. can a

define($dbh3, new PDO(...));//test

statement work? can I call a PDO object as a global constant?
How can I create a common pdo connection? Do I have to create a pdo object in each function?

Current Situation:

$dbh = new PDO(...);
define($dbh3, new PDO(...));//test

function actorexists($name) {
  $dbh = new PDO(...);
  $s = $dbh->prepare("...");
}

function login($name, $password) {
  $dbh = new PDO(...);
  $s = $dbh->prepare("..."}
}

function actorbyname($name) {
  $dbh = new PDO(...);
  $s = $dbh->prepare("...;
}

Answer 1

I would not define the object as a constant. Given your example, you can inject it where you need it.

function actorexists($pdo, $name) {
  $s = $pdo->prepare("...");
}

function login($pdo, $name, $password) {
  $s = $pdo->prepare("...");
}

function actorbyname($pdo, $name) {
  $s = $pdo->prepare("...");
}

$dbh = new PDO("...");
$exists = actorexists($dbh, 'foo');
$foo = actorbyname($dbh, 'foo');