Topic: Connecting in a PDO Database Class

[seaweed]

I have a database class that uses PDO prepared statements. The connection is like this:

public function dbConnect() {
   $this->_dbh = new PDO('mysql:host=localhost; dbname=db_name', 'username', 'password');
}

I have a few questions about it.

1. Should I put this code in my constructor method?

2. Should I set $dbh = null; at the end of the script or leave it open?
    This application will be hammering this class with queries non-stop,
    it's the crux of the website, looking up products in a catalog.

[ignace]

1. Should I put this code in my constructor method?

No.

2. Should I set $dbh = null; at the end of the script or leave it open?
    This application will be hammering this class with queries non-stop,
    it's the crux of the website, looking up products in a catalog.

Db connections are automatically closed at the end of the script so you can't leave it open not even with the persistent option.

Plus you should be using something like:

class Db extends PDO implements Db_Interface

This decouples PDO from your models as the same could have been written:

class Db extends MySQLi implements Db_Interface

While your models only expect:

class MyModel {
    public function __construct(Db_Interface $db) {

Altough the above method (class Db extends ..) is not encouraged and an approach with a factory method and adapter pattern is encouraged

Also always remember to lazy-load:

interface Db_Interface {
    public function connect();
    public function query($sql);
}

class MyDb extends PDO implements Db_Interface {
    public function query($sql) {
        $this->connect();
        //..
    }
}

A connection is made only when it is absolutly needed.