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POIs it good or bad practise to alter start dates in a database to the next occurrence of an event?
 

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  1. POIs it good or bad practise to alter start dates in a database to the next occurrence of an event?
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    <p>I am trying to create an event calendar which whilst initially quite small could turn out to be quite large. To that end, when trying to future proof it as much as possible, all events that occur in the past will be deleted from the database. However, is it bad practise to alter the start date of recurring events once they have happened to indicate when the next event will start? This makes it easier to perform search queries because theoretically no events will start more than say a week in the past, depending on how often the database is updated.</p> <p>Is there a better way to do this?</p> <p>My current intention is to have a table listing the event details along with a column for whether it is a yearly, monthly, weekly or daily recurrence. When somebody then searches for events between 2 dates, I simply look at each row and check if (EVENT START &lt;= SEARCH FINISH &amp;&amp; EVENT FINISH >= SEARCH START). This then gets all the possible events, and the recurring ones then need to be checked to see if they occur during the time period given. This is where I come a little unstuck, as to how to achieve this specifically. My thoughts are as follows:</p> <p>Yearly: if EVENT START + 1 YEAR &lt;= SEARCH FINISH || EVENT FINISH + 1 Year >= SEARCH START; repeat for +2 YEARS etc until EVENT START + NO YEARS > SEARCH FINISH.</p> <p>Monthly: As above but + 1 month each time.</p> <p>Weekly: As above but EVENT START and EVENT FINISH will be plus 7 DAYS BETWEEN RECURRENCE each iteration until EVENT START + 7 DAYS REPEATED > SEARCH FINISH.</p> <p>Daily: As above but NO OF DAYS DIFFERENCE instead of 7 days for a week. This could be used to specify things like every 14 days (fortnight), every 10 days. Even every week could use this method.</p> <p>However, when I think about the query that would have to be built to achieve this, I cannot help think that it will be very cumbersome and probably slow. Is there a better way to achieve the results I want? I have still not found a way to do things like occurs on the first Monday of a month or the last Friday of a month, or the second Saturday of April each year. Are these latter options even possible?</p> <p>-- Edit: added below:</p> <p>It might help a bit if I explain a bit more about what I am creating. That way guidance can be given with respect to that.</p> <p>I am creating a website which allows organisations to add events, whether they are a one-off or recurring (daily, weekly, monthly, first Tuesday of a month etc.). The user of the site will then be able to search for events within a chosen distance (arbitrary 10, 25, 50, 100miles, all of country) on a set date or between 2 given dates which could be from 1 day apart up to a couple of years apart (obviously events that far into the future will be minimal or non-existant depending on the dates used).</p> <p>The EVENTS table itself currently holds a lot of information about the event, such as location, cost, age group etc. Would it be better to have this in a separate table which is looked up once it has been determined if the event is within the specified search parameters? Clearly not all of this information is needed until the detailed page view, maybe just a name, location, cost and brief description.</p> <p>I appreciate there are many ways to skin a cat but I am unsure how to skin this one. The biggest thing I am struggling with is how to structure my data so that a query will know if the recursion is within the specified date. Also, given that the mathematics to calculate distance between 2 lat/longs is relatively complex, I need to be able to build this calculation into my query, otherwise I will be doing the calculation in PHP anyway. Granted, there will be less results to process this way, but it still needs to be done.</p> <p>Any further advice is greatly appreciated.</p>
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