I'm new to SQL and I'm trying to set up a log-in system. I've followed a guide but I'm getting these 2 messages when I try to login:
Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given in C:\xampp\htdocs\loginguide/login.php on line 13
Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given in C:\xampp\htdocs\loginguide\login.php on line 16
I created a database on MyPHPAdmin however, I don't know how to do that properly either, am I meant to add tables to that database?
Here's the login.php code:
<?php
   include("config.php");
   session_start();
   if($_SERVER["REQUEST_METHOD"] == "POST") {
      // username and password sent from form 
      $myusername = mysqli_real_escape_string($db,$_POST['username']);
      $mypassword = mysqli_real_escape_string($db,$_POST['password']); 
      $sql = "SELECT id FROM admin WHERE username = '$myusername' and passcode = '$mypassword'";
      $result = mysqli_query($db,$sql);
      $row = mysqli_fetch_array($result,MYSQLI_ASSOC);
      $active = $row['active'];
      $count = mysqli_num_rows($result);
      // If result matched $myusername and $mypassword, table row must be 1 row
      if($count == 1) {
         session_register("myusername");
         $_SESSION['login_user'] = $myusername;
         header("location: welcome.php");
      }else {
         $error = "Your Login Name or Password is invalid";
      }
   }
?>
<html>
   <head>
      <title>Login Page</title>
      <style type = "text/css">
         body {
            font-family:Arial, Helvetica, sans-serif;
            font-size:14px;
         }
         label {
            font-weight:bold;
            width:100px;
            font-size:14px;
         }
         .box {
            border:#666666 solid 1px;
         }
      </style>
   </head>
   <body bgcolor = "#FFFFFF">
      <div align = "center">
         <div style = "width:300px; border: solid 1px #333333; " align = "left">
            <div style = "background-color:#333333; color:#FFFFFF; padding:3px;"><b>Login</b></div>
            <div style = "margin:30px">
               <form action = "" method = "post">
                  <label>UserName  :</label><input type = "text" name = "username" class = "box"/><br /><br />
                  <label>Password  :</label><input type = "password" name = "password" class = "box" /><br/><br />
                  <input type = "submit" value = " Submit "/><br />
               </form>
               <div style="font-size:11px;<?php echo $error; ?></div>
            </div>
         </div>
      </div>
   </body>
</html>