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PORepeating calendar events and some final maths
 

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  1. PORepeating calendar events and some final maths
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    <p>I am trying to have a go at the infamous repeating events on calendars using PHP/MySQL. I've finally found something that seems to work. I found my <a href="https://stackoverflow.com/a/5186095/158126">answer here</a> but I'm having a little difficulty finishing it off.</p> <p>My first table 'events'.</p> <pre><code>ID NAME 1 Sample Event 2 Another Event </code></pre> <p>My second table 'events_meta that stores the repeating data.</p> <pre><code>ID event_id meta_key meta_value 1 1 repeat_start 1336312800 /* May 7th 2012 */ 2 1 repeat_interval_1 432000 /* 5 days */ </code></pre> <p>With repeat_start being a date with no time as a unix timestamp, and repeat_interval an amount in seconds between intervals (432000 is 5 days). </p> <p>I then have the following MySQL which I modified slightly from the above link. The timestamp used below (1299132000 which is 12th May 2012) is the current day with no time.</p> <pre><code>SELECT EV.* FROM `events` EV RIGHT JOIN `events_meta` EM1 ON EM1.`event_id` = EV.`id` RIGHT JOIN `events_meta` EM2 ON EM2.`meta_key` = CONCAT( 'repeat_interval_', EM1.`id` ) WHERE EM1.meta_key = 'repeat_start' AND ( ( CASE ( 1336744800 - EM1.`meta_value` ) WHEN 0 THEN 1 ELSE ( 1336744800 - EM1.`meta_value` ) / EM2.`meta_value` END ) ) = 1 </code></pre> <p>In the above MySQL, the following code deducts the repeat_start field (<code>EM1.'meta_value'</code>) from the current date and then divides it by the repeat interval field (<code>EM2.'meta_value'</code>).</p> <pre><code>ELSE ( 1336744800 - EM1.`meta_value` ) / EM2.`meta_value` </code></pre> <p>OR</p> <pre><code>TODAYS DATE - START DATE / 5 DAYS </code></pre> <p>So here's the maths:</p> <pre><code>1336744800 - 1336312800 = 432000 432000 / 432000 = 1 </code></pre> <p>Now that works perfect. But if I change the current timestamp 5 days ahead to 1336312800 which is 17th Mat 2012, it looks a bit like this:</p> <pre><code>1336312800 - 1336312800 = 864000 86400 / 432000 = 2 </code></pre> <p>Which doesn't work because it equals 2 and in the MySQL it needs to equal 1. So I guess my question is, how do I get the MySQL to recognise a whole number rather than having to do this?</p> <pre><code>... WHERE EM1.meta_key = 'repeat_start' AND ( ( CASE ( 1336744800 - EM1.`meta_value` ) WHEN 0 THEN 1 ELSE ( 1336744800 - EM1.`meta_value` ) / EM2.`meta_value` END ) ) = IN (1,2,3,4,5,6,7,8,....) </code></pre> <p>Hope I'm making sense and I hope it's just a simple maths thing or a function that MySQL has that will help :) Thanks for your help!</p> <p><strong>EDIT: THE ANSWER</strong></p> <p>Thanks to @eggypal below, I found my answer and of course it was simple!</p> <pre><code>SELECT EV.* FROM elvanto_calendars_events AS EV RIGHT JOIN elvanto_calendars_events_meta AS EM1 ON EM1.`event_id` = EV.`id` RIGHT JOIN elvanto_calendars_events_meta AS EM2 ON EM2.`meta_key` = CONCAT( 'repeat_interval_', EM1.`id` ) WHERE EM1.meta_key = 'repeat_start' AND ( ( 1336744800 - EM1.`meta_value` ) % EM2.`meta_value`) = 0 </code></pre>
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    1. CODate math based on timestamps and fixed number of seconds in a day will break on Daylight Savings.
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    2. COGood call @DCoder. I store all my times as GMT and then use the CONVERT_TZ function to determine the `repeat_start` date. The above code examples doesn't include this extra code. I think that should do the trick right?
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    3. COwill your query allow me to see the result for the given start date and end date? `1336744800 ` looks like a specific day :(
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      1. USMurali Murugesan
 

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