Select 2 different values from 2 different tables in a single $sql query

Question

I want to select the firstName and lastName from a different table, but im having some issues, I'll paste the code down below.

The table orders does not contain the firstName and lastName, so I want to call firstName and last name from from table users, but I don't know how. I want help with the query!

<?php $sql = "SELECT * from orders";

    //In this line above i also want to select firstName and lastName from table users

    $result = mysqli_query($conn, $sql);
    $counter = 0;
    while($row = mysqli_fetch_assoc($result)){
        $Id = $row['userId'];
        $orderId = $row['orderId'];
        $firstName = $row['firstName'];
        $lastName = $row['lastName'];
        $address = $row['address'];
        $zipCode = $row['zipCode'];
        $phoneNo = $row['phoneNo'];
        $amount = $row['amount'];
        $orderDate = $row['orderDate'];
        $paymentMode = $row['paymentMode'];

        if ($paymentMode == 0) {
            $paymentMode = "Cash on Delivery";
        } else {
            $paymentMode = "Online";
        }
        $orderStatus = $row['orderStatus'];
        $counter++;
                    
        echo '<tr>
            <td>' . $orderId . '</td>
            <td>' . $Id . '</td>
            <td>' . $firstName . '</td>
            <td>' . $lastName . '</td>
            <td data-toggle="tooltip" title="' .$address. '">' . substr($address, 0, 20) . '...</td>
            <td>' . $phoneNo . '</td>
            <td>' . $amount . '</td>
            <td>' . $paymentMode . '</td>
            <td>' . $orderDate . '</td>
            <td><a href="#" data-toggle="modal" data-target="#orderStatus' . $orderId . '" class="view"><i class="material-icons">&#xE5C8;</i></a></td>
            <td><a href="#" data-toggle="modal" data-target="#orderItem' . $orderId . '" class="view" title="View Details"><i class="material-icons">&#xE5C8;</i></a></td>
        </tr>';
    }
    if ($counter==0) {
?>
<script>
document.getElementById("NoOrder").innerHTML = '<div class="alert alert-info alert-dismissible fade show" role="alert" style="width:100%"> You have not Recieve any Order!  </div>';</script>

<?php`
    } 
?> 

I've tried may query methods but none of them worked so I could need some help from professionals

Answer 1

Use INNER JOIN,

If your orders table is orders and users table is users.

You can construct a query like below,

SELECT o.*, u.firstName as firstName, u.lastName as lastName FROM orders o INNER JOIN users u ON o.user_id = u.id.

Provided you have user_id column in orders table with value equal to primary key of users table.