Database in php can be Created by using the four argumnets:-
Servername,Username,Password and dbname.

This will give the information about the server like a using 'localhost' username as 'root' and password should be of users choice and the daname is the users database name.
 For creating the connection user use the querry  below

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

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

$sql = "INSERT INTO database(id, name, salary)
VALUES ('43483', 'shristi', '10000')";

if ($conn->query($sql) === TRUE) {
    echo "New record created successfully";
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

$conn->close();
?>