How to connect to a new database using PHP MySQL

Question

So I've been trying to learn how to use MySQL with PHP, and I've managed to create a connection and create a database along with a table. What I don't know how to do is create the database along with the tables all in one go.

What I mean by this is easier shown in my code (Which will show unable to connect error message because the connect method is trying to connect to a database that does not exist.

    <?php
    $servername = isset($_POST["servername"]) ? $_POST["servername"] : '';
    $username = $_POST["username"];
    $password = $_POST["password"];
    $dbname = $_POST["dbname"];

    // Create connection
    $conn = mysqli_connect($servername, $username, $password, $dbname);
    // Check connection
    if (!$conn) {
        die("Connection failed: " . mysqli_connect_error());
    }

    // Create database
    $sql = "CREATE DATABASE myDB";
    if ($conn->query($sql) === TRUE) {
        echo "Database created successfully";
    } else {
        echo "Error creating database: " . $conn->error;
    }

    // sql to create table
    $sql = "CREATE TABLE MyGuests (
    id INT(6) UNSIGNED AUTO_INCREMENT PRIMARY KEY,
    firstname VARCHAR(30) NOT NULL,
    lastname VARCHAR(30) NOT NULL,
    email VARCHAR(50),
    reg_date TIMESTAMP
    )";

    if (mysqli_query($conn, $sql)) {
        echo "Table MyGuests created successfully";
    } else {
        echo "Error creating table: " . mysqli_error($conn);
    }
    mysqli_close($conn);
    ?> 

So, all I am trying to achieve is Connect to MySQL, create the database, create a table for said database and close the connection all within one .php file.

On a side note, due to the user being able to define a database name ( $dbname ), how would I add this value into the MySQL code above? I heard somewhere that you're supposed to add the variable into quotes? So '$dbname' . Any help with that would be good too! Thanks in advance!

Okay, the reason for this question is because I am creating a setup-type page where the user will be able to connect to their own database, allowing them to give it a name and connect using their credentials. Obviously I am not very experienced within this field, I hope I have explained it better.

Answer 1

All the code you have looks fine to me. The only thing I think your missing is after you create a database you have to call

$conn->select_db("myDB");

Also if you want to have the database name be $dbname then

$sql = "CREATE DATABASE myDB";

should be

$sql = "CREATE DATABASE " . $dbname;

If I didn't cover your problem please give me more detail on your problem.

Answer 2

where you passing all of this variable ?

$servername = isset($_POST["servername"]) ? $_POST["servername"] : '';
$username = $_POST["username"];
$password = $_POST["password"];
$dbname = $_POST["dbname"];

just simply hardcode the servername, username, password and your dbname.