title: mongodb regular expressions matching
body: <p>i am having these kind of strings</p>
  
  <pre><code>"abc?ref1=app";
  
  "abc?ref1=app&amp;xxxxxxxxxxxxxxxxxxxxxxxxxxx"
  </code></pre>
  
  <p>where xxxxxxxxxxxxxxx is some string...</p>
  
  <p>i want to write regular expression which should only match <code>"abc?ref1=app"</code> types of strings and should not match any other string like <code>"abc?ref1=app&amp;xxxxxxxxxxxxxxxxxxxxxxxxxxx"</code> ..i mean it should only and only match <code>"abc?ref1=app"</code> type of strings...</p>
  
  <p>i have written some thing like this <code>/abc\?ref1=app/</code> ..but this will also match <code>"abc?ref1=app&amp;xxxxxxxxxxxxxxxxxxxxxxxxxxx"</code></p>
  
  <p>please tell me how to write regular expression which will only match <code>"abc\?ref1=app"</code></p>