title: PHP variables don't evaluate in the query
body: <p>I am pretty new to PHP and MySQL and I just can't figure this one out. I have searched all around the forum but haven't found an answer I can make sense of. I originally was using mysql_fetch_assoc() but I could only search numbers and I received errors when searching for letters as well. I hope I am on the right track here. Thank you in advance for all your help!</p>
  
  <pre><code>$con = mysqli_connect($hostname,$username,$password) or die ("&lt;script language='javascript'&gt;alert('Unable to connect to database')&lt;/script&gt;");
  mysqli_select_db($con, $dbname);
  
  if (isset($_GET['part'])){
      $partid = $_GET['part'];
      $sql = 'SELECT * 
          FROM $usertable 
          WHERE PartNumber = $partid';
  
      $result = mysqli_query($con, $sql);
      $row = mysqli_fetch_assoc($result);
  
      $partnumber = $partid;
      $nsn = $row["NSN"];
      $description = $row["Description"];
      $quantity = $row["Quantity"];
      $condition = $row["Conditio"];
  }
  </code></pre>