PHP PDO - Testing connection before doing query? - mysql

Question

public function smart_query($query, $options = null, $bindoptions = null)
{
// Code to Reconnect incase of timeout
try {
$this->db->query('SELECT * FROM templates');
}
catch (PDOException $e)
{
echo $e;
$pdooptions = array(
PDO::ATTR_PERSISTENT => true,
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
);
$this->db = new PDO("mysql:host=localhost;dbname=$this->database", "$this->username", "$this->password", $pdooptions);
}
$this->statement = $this->db->prepare($query);
if($bindoptions != null)
{
$this->bind($bindoptions);
}
$this->execute();
if($options != null)
{
// Return Single Row
if($options['rows'] == 1)
{
return $this->statement->fetch(PDO::FETCH_ASSOC);
}
// Return Multiple Rows
elseif($options['rows'] != 1)
{
return $this->statement->fetchAll(PDO::FETCH_ASSOC);
}
}
}
I've saw this code today, and got really confused.
It looks like he is trying to process a simple query, before doing the actual query.
Why is he checking if the connection is still open?
I thought that PDO only destroys it's connection upon script finishing executing automatically?
Is that correct to check if it's open or closed?

Answer 1

This implements a form of lazy loading.
This first time a query is executed through this class/function, the database connection may not be established yet. This is the purpose of this check, so that the consumer (you) does not have to mind about it.
The connection is then stored in the $this->db class member, for future reuse when you call this method again in the course of your script (and yes, this connection will stay open until the script ends -- unless it is closed explicitely beforehand, of course).
For information, this check is slightly inefficient. A simple $this->db->query('SELECT 1') would suffice, without the need to read a table at all.