如何在postgresql中循環時選擇多個列？

Question

請告訴我如何做到這一點我想選擇多列同時循環..

create or replace function insert_date_dimension("date" date) 
returns setof date as $$ 
declare 
    dat date; 
    start_date date; 
    end_date date; 
begin 
    start_date := '2016/01/01'; 
    end_date := '2016/12/31'; 
    while start_date <= end_date loop 
     --return next start_date; 
     select start_date,date_part('week',start_date),date_part('quarter',start_date),to_char(start_date, 'day'),to_char(start_date, 'month'), 
     extract(year from current_date),extract(month from current_date); 
     start_date:= start_date + interval '1 day'; 
    end loop; 
end; 

$$語言PLPGSQL;

ERROR: query "SELECT start_date,date_part('week',start_date),date_part('quarter',start_date),to_char(start_date, 'day'),to_char(start_date, 'month'), 
     extract(year from current_date),extract(month from current_date)" returned 7 columns 

背景：PL/pgSQL函數insert_date_dimension（日）線11在RETURN NEXT

Answer 1

錯誤發生，因爲你必須在PL/pgSQL函數使用SELECT ... INTO ...。此外，你忘了RETURN的東西。

使用generate_series要容易得多;這樣你可能甚至不需要定義一個函數，你可以使用INSERT INTO ... SELECT ...。

這裏是因爲我會寫它的函數：

CREATE OR REPLACE FUNCTION insert_date_dimension(
    OUT "date" date, 
    OUT week integer, 
    OUT quarter integer, 
    OUT dayname text, 
    OUT monthname text, 
    OUT year integer, 
    OUT month integer 
) RETURNS SETOF RECORD STABLE LANGUAGE plpgsql AS 
$$DECLARE 
    dat date; 
    start_date timestamp := '2016-01-01 00:00:00'; 
    end_date timestamp := '2016-12-31 00:00:00'; 
BEGIN 
    RETURN QUERY SELECT 
     d::date, 
     date_part('week', d)::integer, 
     date_part('quarter', d)::integer, 
     to_char(d, 'day'), 
     to_char(d, 'month'), 
     date_part('year', d)::integer, 
     date_part('month', d)::integer 
     FROM generate_series(start_date, end_date, '1 day') d(d); 
END;$$;