title: Date Field data types varchar are incompatible with subtract operator in SSMS
body: <p>I've tried to search the answer for this but none of the solutions I've found have worked.</p>
  
  <p>I need to subtract 2 date fields from one other: datearrival - date departed but these are both varchar and so the subtract operator won't work.</p>
  
  <p>Can someone give me an answer in code, perhaps using cast and/or date diff to make this work?</p>
  
  <p>my current code is:</p>
  
  <pre><code>DATEDIFF(dd,[ARRIVDAT],current_timestamp)-(dd,[DEPARTDAT],currenttimestamp) AS LengthOfStay
  </code></pre>
  
  <p>This is highlighting the column names as not being recognised, even though in the rest of the query the multi-bound identifiers are fine.</p>
  
  <p>Any good answers please?</p>