title: Select records matching concat value of two fields in mongodb
body: <p>Is there a way to do something like this on MongoDB?</p>
  
  <pre class="lang-sql prettyprint-override"><code>select * from table where concat(field1, field2) = 'value'
  </code></pre>
  
  <p>To clarify, I have an array of full names, but the documents have firstname and lastname separate, so I want to do something like:</p>
  
  <pre class="lang-sql prettyprint-override"><code>select * from table where concat(firstname, lastname) in ([ARRAY OF NAMES])
  </code></pre>