title: TSQL Update DATETIME Minutes and Seconds
body: <p>I've been staring at this for quite a while and can't figure out how to go about doing it.  I don't really have any code to post because I haven't even gotten close to figuring it out yet and everything I come up with just doesn't make any sense.</p>
  
  <p>Anyways, we have an application that collects data every 5 minutes based on the max(readtime) in the table (but also will only show real values if the time is a multiple of 5 and is at :00.000 seconds.)  For the most part, this is fine, but sometimes the data will get out of sync and cause a bunch of 0 values in our table.</p>
  
  <p>Currently, we've just been going in, grabbing the latest readtime, and hardcoding the new date that we'd like to use.  I'm looking for a script I can use to automate this.  For the purposes of this question, we can use GETDATE().</p>
  
  <pre><code>DECLARE @readtime DATETIME = GETDATE()  --2011-08-09 08:51:19.237
               -- I want it to look like    2011-08-09 08:50:00.000
  </code></pre>