<?php
    $con=mysqli_connect("","username" ,"password","databasename");
    if (mysqli_connect_errno())
     {
      echo "Failed to connect to MySQL: " . mysqli_connect_error();
     }
     ?>

<?php
    $con = mysqli_connect("localhost","username" ,"password","databasename");

    if (mysqli_connect_errno())
    {
        echo "Failed to connect to MySQL: " . mysqli_connect_error();
    }
?>

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

    // Create connection
    $con = mysqli_connect($servername, $username, $password);

    // Check connection
    if (!$con) {
        die("Connection failed: " . mysqli_connect_error());
    }
    echo "Connected successfully";
?>

$servername = "localhost";
$username = "root";
$password = "";

$localhost = "localhost";
    $root = "root";
    $password = "";
    $con = mysql_connect($localhost,$root,$password) or die('Could not connect to database');
    mysql_select_db("db_name",$con);

$con = mysqli_connect("localhost","username" ,"password","databasename");

service mysqld start

mysql -u root

mysql -u root -p

$hostname='localhost';
$username='root';
$password='';

try {
  $dbh = new PDO("mysql:host=$hostname;dbname=dbname",$username,$password);
}
catch(PDOException $e) {
 echo $e->getMessage();
}

$con=mysqli_connect("current_server_IP","username" ,"password","databasename");

<?php

$servername="";
$username="";
$password="";
$db="";

$conn=mysqli_connect($servername,$username,$password,$db);
//mysql_select_db($db);
if (!$conn) {
    echo "Error: Unable to connect to MySQL." . PHP_EOL;
    echo "Debugging errno: " . mysqli_connect_errno($conn) . PHP_EOL;
    echo "Debugging error: " . mysqli_connect_error($conn) . PHP_EOL;
    exit;
}
@session_start();

$event_name = $_POST['first_name'];
$first_name = $_POST['last_name'];

$sql = "INSERT INTO customer(first_name, last_name,) VALUES ('$first_name', '$last_name')";

$conn->query($sql);
$lastInsertId = mysqli_insert_id($conn);

?>