title: Retrieve a list of records based on time intervals (PHP/MySQL)
body: <p>In my database table I have a DATETIME field called 'start_datetime'.</p>
  
  <p>The time portion is always stored based on 5 min intervals, with no seconds, for example: 15:25:00 or 12:10:00 or 17:30:00</p>
  
  <p>Now I need to set up a CRON task which will send out an email exactly 2 days before 'start_datetime'.</p>
  
  <p>There are a couple of issues here:</p>
  
  <p>1) First of all I need to FIND all records with a 'start_datetime' that is exactly 2 days before NOW (i.e. the time of running the query)</p>
  
  <p>2) It should ignore any records that are more than, or less than 2 days away. Considering the times are based on 5 min intervals, I can only assume the CRON task would have to run every 5 mins? This could be a problem because my hosting provider only allows a CRON to run once every hour max.</p>
  
  <p>So what is the best way to approach this?</p>