PHP global in functions

Question

What is the utility of the global keyword?

Are there any reasons to prefer one method to another?

• Security?
• Performance?
• Anything els

Answer 1

It makes no sense to make a concat function using the global keyword.

It's used to access global variables such as a database object.

Example:

function getCustomer($id) {
  global $db;
  $row = $db->fetchRow('SELECT * FROM customer WHERE id = '.$db->quote($id));
  return $row;
}

It can be used as a variation on the Singleton pattern