我想创建一个函数来获得正确的一周数.
我已经发布了 here以找到“原生”解决方案,但显然没有.
我已经发布了 here以找到“原生”解决方案,但显然没有.
我试图根据这个mysql example创建功能
CREATE OR REPLACE FUNCTION week_num_year(_date date)
RETURNS integer AS
$BODY$declare
_year integer;
begin
select date_part('year',_date) into _year;
return ceil((to_char(_date,'DDD')::integer+(to_char(('01-01-'||_year)::date,'D')::integer%7-7))/7);
end;$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
但它给出了错误的结果,有人可以帮助我吗？
我的配置：Postgresql 9.2
create or replace function week_num_year(_date date)
returns integer as
$body$
declare
_year date;
_week_number integer;
begin
select date_trunc('year',_date)::date into _year
;
with first_friday as (
select extract(doy from a::date) ff
from generate_series(_year,_year + 6,'1 day') s(a)
where extract(dow from a) = 5
)
select floor(
(extract(doy from _date) - (select ff from first_friday) - 1) / 7
) + 2 into _week_number
;
return _week_number
;
end;
$body$
language plpgsql immutable
