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    <p>If I understand correctly, you're trying to save this new data about wet periods and dry periods back into the rows, to save for later use? </p> <p>I assume this is so that as each new day is added, it's easy to re-calculate .... or because the data is moving onto somewhere else? </p> <p>Anyway, if this is the case, then one way you could go about it is by having two new columns: 'wet_count" and "dry_count". Count through each row. If the row's wet/dry value matches that of the day before, then increment that value. If it doesn't, zero the values and set the appropriate one to the new value. As such:</p> <pre><code>day rainfall wet_count dry_count Feb 1 1 1 0 Feb 2 0.5 2 0 Feb 3 0.75 3 0 Feb 4 0 0 1 Feb 5 0 0 2 Feb 6 0 0 3 Feb 7 0.5 1 0 Feb 8 1.25 2 0 Feb 9 1.5 3 0 Feb 10 3.5 4 0 Feb 11 4.5 5 0 </code></pre> <p>Then you can simply pull the max value from the table, go back to the first 1 in that column prior to that date, and you have your 'largest period' and 'when it started'.</p> <p>On each new day's data, you only need to calculate versus the previous day, then run two very simple database searches to get the new 'largest period'.</p> <p>More specifically - you pull the distinct values of 'wet_count', ordered descending, and take only the first answer. You do a select on the database where all wet_count = that max, or 1. and you get the number of wet periods that match that particular value, plus the possible start dates. The 1 immediately prior to the max value will be the start date.</p>
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    1. POMySQL calculation for rainfall
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    1. COHi, now actually I only want it as an output on that particular site, no changes in the db, so this wouldnt probabl work
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    2. COAh, I misunderstood. Apologies.
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    3. COSure, thanks anyway
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