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POMYSQL QUERY replace NULL value in a row with average values
 

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    <p>I'm using a mysql database to store huge amount of satellite data, and these datasets has many data-gaps. I would like to replace the NULL values with an 1 hour(or less) average around that point. So far I've found how to replace the NULL value with the previous known value:</p> <pre><code>UPDATE mytable SET number = (@n := COALESCE(number, @n)) ORDER BY date; </code></pre> <p>from this post: <a href="https://stackoverflow.com/questions/1345065/sql-query-replace-null-value-in-a-row-with-a-value-from-the-previous-known-value">SQL QUERY replace NULL value in a row with a value from the previous known value</a></p> <p>My table looks like</p> <pre><code>+---------------------+--------+ | date | P_f | +---------------------+--------+ | 2001-01-01 20:20:00 | 1.88 | | 2001-01-01 20:25:00 | NULL | | 2001-01-01 20:30:00 | NULL | | 2001-01-01 20:35:00 | 1.71 | | 2001-01-01 20:40:00 | NULL | | 2001-01-01 20:45:00 | NULL | | 2001-01-01 20:50:00 | NULL | | 2001-01-01 20:55:00 | 1.835 | | 2001-01-01 21:00:00 | 1.918 | | 2001-01-01 21:05:00 | 1.968 | | 2001-01-01 21:10:00 | 2.004 | | 2001-01-01 21:15:00 | 1.924 | | 2001-01-01 21:20:00 | 1.8625 | | 2001-01-01 21:25:00 | 1.94 | | 2001-01-01 21:30:00 | 2.0375 | | 2001-01-01 21:35:00 | 1.912 | </code></pre> <p>I'd like to replace the NULL values with average values around that datetime. For instance I'd like to replace ,</p> <pre><code>| 2001-01-01 20:50:00 | NULL | </code></pre> <p>with an average around </p> <pre><code>select AVG(P_f) from table where date between '2001-01-01 20:30' and '2001-01-01 21:10'; </code></pre> <p>Paul</p>
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    1. COis it a one time operation?
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    2. CO@newtover, yes. Tom Mac's solution was spot on. Thanks for showing interest. -Paul
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