Conexión a distintos drivers con PDO

Bienvenid@s, hoy veremos la estructura que debemos seguir para conectar a los siguientes drivers: mysql, sqlite, pgsql y sqlsrv. Todos ellos son compatibles con la extensión PDO (PHP Data Objects):

mysql

         $driver = 'mysql';
         $dbname = 'dbname';
         $host = 'localhost';
         $user = 'password';
         $password = 'password';
         $connection = new PDO("$driver:dbname=$dbname;host=$host;", $user, $password);

sqlite

         $driver = 'sqlite';
         $dbname = '../application/Database/test.sqlite';
         $connection = new PDO("$driver:$dbname");;

pgsql

         $driver = 'pgsql';
         $dbname = 'dbname';
         $host = 'localhost';
         $port = 5432;
         $user = 'root';
         $password = 'password';
         $connection = new PDO("$driver:host=$host;port=$port;dbname=$dbname;user=$user;password=$password");

sqlsrv

         $driver = 'sqlsrv';
         $dbname = 'dbname';
   $host = 'localhost';
         $user = 'root';
         $password = 'password';
         $connection = new PDO("$driver:Server=$host;Database=$dbname", $user, $password);