Se aggiungi la clausola
HAVING (COUNT(id_p) = 0)
dovresi vedere solo i mesi/anno che non hanno occorrenze:
SELECT DATE_FORMAT(creation_date, '%M %Y') AS Month_Year,COUNT(id_p) AS tot FROM tab1 WHERE
creation_date>='2011-01-01' AND creation_date<='2012-12-31'
GROUP BY YEAR(creation_date),MONTH(creation_date)
HAVING (COUNT(id_p) = 0)
Con questo risultato:
Gen 2011 0
Mar 2011 0
...
Ott 2012 0
Andrea
http://about.me/andrea.melis