title: Adding time(hh:mm:ss) to a datetime field in SQL
body: <p>I want to add the run_duration column(hh:mm:ss) to the run_datetime(datetime) column to calculate the endtime by using the following query:</p>
  
  <pre><code>SELECT checkdate, run_datetime, run_duration,
  cast(run_datetime as datetime) + cast(run_duration as datetime) as readytime, 
  cast(cast(run_datetime as datetime) + cast(run_duration as datetime) as datetime) as readytime_datetime
  FROM table
  </code></pre>
  
  <p>The problem is that it is not adding up correctly for some records because it is summing above the 60 seconds:</p>
  
  <p><a href="https://i.stack.imgur.com/70glS.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/70glS.png" alt="enter image description here"></a></p>
  
  <p>Is there another way to do this correctly?</p>