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// i tried echoing everything possible but no outcome
    <?php
    include("conn.php");
    if(isset($_POST['btn_login'])){
    $username = $_POST['username'];
    $password = $_POST['password'];

    }
    $sql = "SELECT * FROM users WHERE username='$username' AND password='$password' LIMIT 1";

    $result = mysqli_query($conn,$sql);

    $response = array();
    if(mysqli_num_rows($result)>0){
        $row = mysqli_fetch_row($result);
        $username = $row['username'];
        $password = $row['password'];


        $code = "login_success";
        array_push($response,array("code"=>$code,"username"=>$username,"password"=>$password));
        echo json_encode($response);
    }
    else{
        $code = "login_failed";
        $message = "User not found... Please try again";
        array_push($response, array("code"=>$code,"message"=>$message));
        echo json_encode($response);
    }
    mysqli_close($conn);
    ?>
    <!DOCTYPE html>
    <html>
    <head>
        <title></title>
    </head>
    <body>
    <form method="post">
        <input type="text" name="username">
        <input type="text" name="password">
        <input type="submit" name="btn_login">
    </form>
    </body>
    </html>