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Displaying posts with tag: Median (reset)

Greatest N per group: top 3 with GROUP_CONCAT()
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In my opinion, one of the best things that happened to Planet MySQL lately, is Explain Extended, a blog by Alex Bolenok (also known as Quassnoi on Stackoverflow).

I never had the pleasure of meeting Alex in person, but his articles are always interesting and of high quality, and the SQL wizardry he pulls off is downright inspiring. I really feel humbled by the creativity of some of his solutions and …

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A fast, single pass method to calculate the median in MySQL
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After stepping off of the GROUP_CONCAT() solution for calculating quantiles I figured it would be nice to find a better way to calculate the median too.
Solution
I previously wrote on how to calculate the median using GROUP_CONCAT(), but I think that this is a better way:


SELECT AVG(length) AS median -- take the average of left and right median
, …




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Calculating the Nth percentile in MySQL
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Yesterday, I was on the freenode ##pentaho irc channel when Andres Chaves asked me how to calculate the Nth percentile in MySQL. He saw a solution somewhere using subqueries, but wasn't too happy about it.

A while ago I wrote about calulating the median in MySQL, and it turns out the Nth percentile can be calculated using a similar, single-pass approach, not relying on subqueries, …

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