CREATE or REPLACE FUNCTION insert_p_date() RETURNS text as ```

$$
DECLARE
sql_string text;
sdate timestamp without time zone;
ldate timestamp without time zone;
_wtid integer;
--一段时间内每个月第一天
cur1 cursor for select date(zz) from generate_series(date_trunc('month',to_date('20171001','yyyymmdd')),date_trunc('month',to_date('20180401','yyyymmdd')),'1 month') as tt(zz);
curs2 refcursor;
BEGIN
--打开
open cur1;
loop
fetch cur1 into sdate;
-- 假如没有数据，结束循环
Exit when NOT found;
--一段时间内的最后一个月的最后一天
select (date_trunc('month',sdate) + INTERVAL '1 MONTH - 1 day') into ldate;
--上个月最后一天
--select date_trunc('day', date_trunc('month',sdate)) - interval '1 day' into ldate;
--断点抛出一个月第一天
raise notice 'sdate==================================================================%', sdate;
--定义一个月内的内的所有单台设备
open curs2 for select distinct wtid from statisticdata_bak where rectime between sdate and ldate;
loop
--取记录
fetch curs2 into _wtid;
-- 假如没有检索到数据，结束循环
Exit when NOT found;
--抛出设备信息
raise notice '_wtid=%', _wtid;
--执行数据导入按照设备每个月
sql_string := 'insert into statisticdata select * from statisticdata_bak where wtid='||_wtid||' and rectime between '''||sdate||''' and '''||ldate||''';';
execute sql_string;
raise notice '执行完成=%', _wtid;
end loop;
close curs2;
end loop;
--关闭游标1
close cur1;

--返回结果
RETURN '导入成功！';
END;
$$
LANGUAGE plpgsql;