由用作表达式但仅在函数中使用的子查询返回的多行

Question

当我使用一个函数时，它会给出上面提到的错误，但当单独使用相同的代码时，它工作得很好。这里的问题在哪里？

摆弄功能：https://dbfiddle.uk/?rdbms=postgres_12&fiddle=c4b0c8a59d2bd851284ed624ab1c335d

用干净的选择敲击：https://dbfiddle.uk/?rdbms=postgres_12&fiddle=7ccca6c70061aff1f6c394815aa8e9b1

样本数据：

create table report
(report_day date,
tickets_no integer,
tickets_stake numeric,
promo_tickets_no integer,
promo_tickets_stake numeric,
group_id integer);

insert into report
values
('2020-07-20',12,569.6, 2, 44,1),
('2020-07-20',61,2000, 5, 260,2),
('2020-07-21',35,1244.2, 11, 250,1),
('2020-07-21',100,2500.5, 29, 575,2),
('2020-07-22',66,2511.8, 23, 670,1),
('2020-07-22',125,3358.2, 50, 990,2);
CREATE OR REPLACE FUNCTION report(arguments json)
RETURNS json AS
$BODY$

DECLARE 

dateFrom date;
dateTo date;
selectedType integer;
BEGIN 

dateFrom := cast(arguments->>'dateFrom' as date);
dateTo := cast(arguments->>'dateTo' as date);
selectedType := cast(arguments->>'selectedType' as integer);
RETURN (
WITH full_data as (
with tickets as (
select 
report_day
, sum(tickets_no) as tickets_no
, sum(tickets_stake) as tickets_stake
FROM report
WHERE selectedType = 0
AND report_day between dateFrom and dateTo
GROUP BY 1)

, promo_tickets as (
select 
report_day
, sum(promo_tickets_no) as promo_tickets_no
, sum(promo_tickets_stake) as promo_tickets_stake
FROM report
WHERE selectedType = 1
AND report_day between dateFrom and dateTo
GROUP BY 1)

select 
t.report_day 
, sum(coalesce(t.tickets_no,0) + coalesce(pt.promo_tickets_no,0)) as tickets_no                             
, sum(coalesce(t.tickets_stake,0) + coalesce(pt.promo_tickets_stake,0)) as tickets_no
FROM tickets t
LEFT JOIN promo_tickets pt on t.report_day = pt.report_day                                    
GROUP BY 1
ORDER BY 1)

select row_to_json(full_data) from full_data
);
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;

select * from report(json_build_object('dateFrom', '2020-07-20', 'dateTo', '2020-07-22','selectedType', 0 ))

Answer 1

如果您希望函数像查询一样返回一个报表对象数组，那么请更改这一部分：

select row_to_json(full_data) from full_data

将行聚合为数组：

select json_agg(row_to_json(full_data)) from full_data

如果您希望函数返回多行，则需要进行两项更改：

CREATE OR REPLACE FUNCTION report(arguments json)
RETURNS table (row_to_json json) AS

对于return:

RETURN QUERY (
WITH full_data as (

此处更新了fiddle。

Answer 2

因为您试图从一个只应返回一行的函数中返回多行。在函数中再添加一个参数，最好是主键列(我想是tickets_no(，比如

CREATE OR REPLACE FUNCTION report(arguments json, i_tickets_no int)

并将查询重写为

WITH full_data AS
(WITH tickets AS
(SELECT report_day,
SUM(tickets_no) AS tickets_no,
SUM(tickets_stake) AS tickets_stake
FROM report
WHERE selectedType = 0
AND report_day BETWEEN dateFrom AND dateTo
AND tickets_no = i_tickets_no
GROUP BY 1),
promo_tickets as
(select report_day,
SUM(promo_tickets_no) as promo_tickets_no,
SUM(promo_tickets_stake) as promo_tickets_stake
FROM report
WHERE selectedType = 1
AND report_day BETWEEN dateFrom AND dateTo
GROUP BY 1)

select t.report_day,
SUM(COALESCE(t.tickets_no, 0) + COALESCE(pt.promo_tickets_no, 0)) AS tickets_no,
SUM(COALESCE(t.tickets_stake, 0) +
COALESCE(pt.promo_tickets_stake, 0)) AS tickets_no
FROM tickets t
LEFT JOIN promo_tickets pt
ON t.report_day = pt.report_day
GROUP BY 1
ORDER BY 1)

并通过添加第二个参数进行调用。

演示