title: How to handle recurring dates (dates only) in .NET?
body: <p>I am trying to figure out a good way to handle recurring events in .NET, specifically for an ASP.NET MVC application.  The idea is that a user can create an event and specify that the event can occur repeatedly after a specific interval (e.g. "every two weeks", "once a month" and so on).</p>
  
  <p>What would be the best way to tackle this?  My brainstorming right now is to have two tables:  Job and RecurringJob.  Job is the "master" record and has the description of the job as well a key to what customer it's for, while RecurringJob links back to Job and has additional info on what the occurrence frequency is (e.g. 1 for "once a month") as well as the timespan (e.g. "Weekly", "Monthly").  The issue is how to determine and set the next occurrence of the job since this will have to be something that's done regularly.  I've seen two trains of thought with this: This logic should either be stored in a database column and periodically updated, or calculated on the fly in the code.</p>
  
  <p>Any thoughts or suggestions on tackling this?</p>
  
  <p>Edit: this is for a subscription based web app I'm creating to let service businesses schedule their common recurring jobs easily and track their customers. So a typical use might be to create a "Cut lawn" job for Mr Smith that occurs every month    The exact date isn't important - it's the ability for the customer to see that Mr Smith gets his lawn cut every month and followup with him about it. </p>
  
  <p>Let me rephrase the above to better convey my idea.  A sample use case for the application might be as follows:</p>
  
  <ul>
  <li>User pulls up the customer record for John Smith and clicks the <em>Add Job</em> link.</li>
  <li>The user fills out the form to create a job with a name of "Cut lawn", a start date of 11/15/2009, and selects a checkbox indicating that this job continually occurs.  The user is presented with a secondary screen asking for the job frequency.  The user indicates (haven't decided how at this point - let's assume select lists) that the job occurs once a month.  </li>
  <li>User clicks save.  </li>
  </ul>
  
  <p>Now, when the user views the record for John Smith, they can see that he has a job, "Cut lawn", that occurs every month starting from 11/15/2009.  On the main dashboard when it's one week prior to the assumed start date, the user sees the job displayed with an indicator such as "12/15/2009 - Cut lawn (John Smith)".  A week before the due date someone from the company calls him up to schedule and he says he's going to be out of town until 1/1/2010, so he wants his appointment rescheduled for that date.  Our user can change the date for the job to be 1/1/2010, and now the recurrence will start one month from that date (e.g. next time will be 2/1/2010).  The idea behind this is that the app is targeting businesses like lawn care, plumbers, carpet cleaners and the like where the exact date isn't as important (because it can and will change as people are busy), the key thing is to give the business an indicator that Mr. Smith's monthly service is coming up, and someone should give him a call to determine when exactly it can be scheduled for.  In effect give these businesses a way to track repeat business and know when it's time to followup with a customer.</p>