PHP

php pdo connection

$host     = "localhost";//Ip of database, in this case my host machine    
$user     = "root";	//Username to use
$pass     = "qwerty";//Password for that user
$dbname   = "DB";//Name of the database

try {
    $connection = new PDO("mysql:host=$host;dbname=$dbname", $user, $pass);
    $connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

}catch(PDOException $e)
{
  echo $e->getMessage();                         
}

PDO connect

<?php
$db = new PDO('mysql:host=myhost;dbname=mydb', 'login', 'password');

pdo connection

<?php
$servername = "localhost";
$username = "root";
$password = "";

try {
  $conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password);
  // set the PDO error mode to exception
  $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
  echo "Connected successfully";
} catch(PDOException $e) {
  echo "Connection failed: " . $e->getMessage();
}
?>

pdo connection

//In this PHP DATA OBJECT (PDO) CONNECTION I am gonna use 
//the exception code that will help hide your database login 
//details from your users if there is an exception (error).
 //dbname(database name)
 //charset(characters encoding )

  try {
    $pdo = new PDO('mysql:host=localhost;dbname=joke;charset=utf8','username','password');
    $pdo->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
  echo 'Successfully Connected to the database';
  } catch (PDOException $e) {
    echo 'ErrorException'.$e->getMessage().'in'.$e->getFile().$e->getCode().$e->getLine();
  } 

connect pdo

$host = '127.0.0.1';
$db   = 'test';
$user = 'root';
$pass = '';
$charset = 'utf8mb4';

$dsn = "mysql:host=$host;dbname=$db;charset=$charset";
$options = [
    PDO::ATTR_ERRMODE            => PDO::ERRMODE_EXCEPTION,
    PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
    PDO::ATTR_EMULATE_PREPARES   => false,
];
try {
     $pdo = new PDO($dsn, $user, $pass, $options);
} catch (PDOException $e) {
     throw new PDOException($e->getMessage(), (int)$e->getCode());
}