which php connection to use if connection is open code example

Example 1: php connect to mysql

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

// Create connection
$conn = new mysqli($servername, $username, $password);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}
echo "Connected successfully";


Simplified

$conn = mysqli_connect('localhost', 'username', 'password');
$database = mysqli_select_db($conn, 'database');

Example 2: db connection in php

Just include this Temlate in other file using PHP Include/Require Keywords
 And Make Connection In One Shot :)

<?php
  
    // echo "Welcome to Connecting of DB Tutorial!";
    // echo "<br>";

    // 1. PDO - Php Data Objects
    // 2. MySQLi extension

    // Set Connection Variable
    $server = "localhost";
    $username = "root";
    $password = "";
    $database = "test";

    // Create A Connection
    $con = mysqLi_connect($server, $username, $password, $database);

     // Check For Connection
     if(!$con){
        die ("Connection Terminated! by Die() function". mysqLi_connect_error());
       
    }
    else {
        echo "Connection Succefully Happened! <br>";
    }


    ?>