endtime 是 timestamp
select to_char(endtime, 'yyyy-MM-dd') as d , count(objectid)
FROM sde.polygon where endtime>='2004-09-01 00:00:00' and endtime <='2004-10-01 23:59:59' group by d
endtime 是 字符串时
select to_char(to_timestamp(endtime::bigint), 'YYYY-MM-DD') as d , count(objectid)
FROM sde.polygon where endtime>='2004-09-01 00:00:00' and endtime <='2004-10-01 23:59:59' group by d
按时统计时，显示24小时
COALESCE设置默认值
select to_char(time, 'yyyy-MM-dd HH24') as d, COALESCE(max(rainfall), 0) as m FROM mis.table_site_rainfall_detail where time>'"+startTime+"' and time <='"+endTime+"' group by d ORDER BY d