AVG, MAX, MIN on meta_value in WordPress If you want to do MAX, MIN, AVG or other kind of mathematical operation on non-numeric MySQL columns (such as longtext for meta_value in WordPress), you can cast it to float like this:

gistfile1.txt

/*
AVG, MAX, MIN on meta_value in WordPress
http://konstruktors.com/blog/wordpress/4554-avg-max-min-meta-value/
*/


SELECT 
    meta_key, 
	MAX(meta_value+0.0) max_meta 
FROM 
	postmeta 
WHERE 
	meta_key='your_key' 
GROUP BY 
	meta_key