Question

更新（对于任何可能坚持这一点的人）：

RETURN QUERY SELECT有效。其他地方写的是PERFORM与void结合使用。所以可能就是这个原因。感谢a_horse_with_no_name的链接。

问题是：

===============

以下是我尝试执行的功能：

CREATE OR REPLACE FUNCTION get_edition_data (date[], OUT fc_copies bigint, OUT cs_copies bigint, OUT ms_copies bigint)
RETURNS SETOF record AS $$
DECLARE 
issue DATE;
BEGIN
FOREACH issue IN ARRAY $1
LOOP
    SELECT
     SUM (
     CASE
     WHEN (edition = 1 AND (period_from <= issue AND period_to >= issue)) THEN
     copies
     ELSE
     0
     END
     ),
     SUM (
     CASE
     WHEN (edition = 2 AND (period_from <= issue AND period_to >= issue)) THEN
     copies
     ELSE
     0
     END
     ),
     SUM (
     CASE
     WHEN (edition = 3 AND (period_from <= issue AND period_to >= issue))  THEN
     copies
     ELSE
     0
     END
     )
    FROM
     public.subscriptions;
     RETURN NEXT;
     END LOOP;
     RETURN;
END;
$$ LANGUAGE plpgsql;

我使用以下方法调用此函数：

SELECT public.get_edition_data(ARRAY[CAST ('2018-01-01' AS DATE)])

在这里我得到错误：

ERROR:  query has no destination for result data
HINT:  If you want to discard the results of a SELECT, use PERFORM instead.
CONTEXT:  PL/pgSQL function get_edition_data(date[]) line 7 at SQL statement

我尝试使用postgres和S.O.的其他地方的例子来创建函数。在某些地方，我看到返回通常指向DECLARE中的记录变量。但在这里，我想循环通过我收到的日期。

-------更新

根据horse_with_no_name提供的内容，我浏览了链接，发现如果我用PERFORM替换SELECT，它可以在plpgsql中使用。现在错误已经沉默。但我没有输出。更新的代码是：

CREATE OR REPLACE FUNCTION get_edition_data (date[], OUT issue date, OUT fc_copies bigint, OUT cs_copies bigint, OUT ms_copies bigint)
RETURNS SETOF record AS $$
DECLARE
issue DATE;
BEGIN
FOREACH issue IN ARRAY $1
LOOP
RAISE NOTICE '%', issue;
    PERFORM
    issue,
     SUM (
     CASE
     WHEN (edition = 1 AND (period_from <= issue AND period_to >= issue)) THEN
     copies
     ELSE
     0
     END
     ),
     SUM (
     CASE
     WHEN (edition = 2 AND (period_from <= issue AND period_to >= issue)) THEN
     copies
     ELSE
     0
     END
     ),
     SUM (
     CASE
     WHEN (edition = 3 AND (period_from <= issue AND period_to >= issue))  THEN
     copies
     ELSE
     0
     END
     )
    FROM
     public.subscriptions;
     RETURN NEXT;
     END LOOP;
     RETURN;
END;
$$ LANGUAGE plpgsql;

我现在正在使用以下内容查询：

SELECT * FROM public.get_edition_data(ARRAY[CAST ('2018-05-01' AS DATE),CAST ('2018-03-01' AS DATE)])

我没有记录，但它循环两次，我收到通知显示日期。

如果我删除所有函数并使用一个简单的select语句，日期硬编码如下：

 SELECT SUM (
     CASE
     WHEN (edition = 1 AND (period_from <= '2018-03-01' AND period_to >= '2018-03-01')) THEN
     copies
     ELSE
     0
     END
     ),
     SUM (
     CASE
     WHEN (edition = 2 AND (period_from <= '2018-03-01' AND period_to >= '2018-03-01')) THEN
     copies
     ELSE
     0
     END
     ),
     SUM (
     CASE
     WHEN (edition = 3 AND (period_from <= '2018-03-01' AND period_to >= '2018-03-01'))  THEN
     copies
     ELSE
     0
     END
     )
    FROM
     public.subscriptions;

我得到以下内容：

sum | sum | sum |
  3 |    0|   0 |

所以有记录和选择查询有效。

Postgres：返回记录 - 错误 - 查询没有结果数据的目的地

0 个答案: