mySQL error with query SELECT itime, SUBSTRING(itime,1,4) AS Year, SUBSTRING(itime,6,2) AS Month, SUBSTRING(itime,9,2) as Day FROM nucleus_item WHERE iblog=1 and itime <="2019-02-21 08:01:51" and idraft=0 and icat=6 GROUP BY Year, Month ORDER BY itime DESC: Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'mdig_ncls1.nucleus_item.itime' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by