Question

我有两张桌子：＆＃34; debt_period＆＃34;和＆＃34;付款＆＃34;。我需要从他们那里看一看。有一种情况可以在一个时期内支付一些款项。因此，在这种情况下，我必须将付款值汇总到一列，并列出另一列中逗号分隔的日期。我使用string_agg（to_char（p.payment_date，＆＃39; DD.MM.YYYY＆＃39;）和窗口函数。这很好用。问题是字符串中的日期不是按时间顺序排列的。我怎么订购它们？

CREATE MATERIALIZED VIEW base.v_period_payments AS
SELECT DISTINCT
dp.card_id,
dp.year, 
dp.month, 
dp.debt_amount, 
string_agg(to_char(p.payment_date, 'DD.MM.YYYY'), ', ') OVER ( PARTITION BY p.period_id) AS 
pay_dates 
FROM base.debt_period dp
LEFT JOIN base.payments p on (p.period_id = dp.id)
WHERE dp.card_id = '№001137'   
ORDER BY dp.card_id

Answer 1

尝试使用这个：

更改

LEFT JOIN base.payments p on (p.period_id = dp.id)

通过

LEFT JOIN  (select * from base.payments  order by period_id,payment_date) p on (p.period_id = dp.id)

最终结果

CREATE MATERIALIZED VIEW base.v_period_payments AS
SELECT DISTINCT
dp.card_id,
dp.year, 
dp.month, 
dp.debt_amount, 
string_agg(to_char(p.payment_date, 'DD.MM.YYYY'), ', ') OVER ( PARTITION BY p.period_id) AS 
pay_dates 
FROM base.debt_period dp
LEFT JOIN  (select * from base.payments  order by period_id,payment_date) p on (p.period_id = dp.id)
WHERE dp.card_id = '№001137'   
ORDER BY dp.card_id

Answer 2

我一直在寻找这种功能，@ Mesbah回答的还有另一种方法

请参阅此处： https://www.postgresql.org/docs/9.0/sql-expressions.html 4.2.8。窗口函数调用

基本上，您可以定义o OR BY BY，OVER BY以及指定要在窗口中包括哪些行（在下面的示例中，该窗口覆盖所有行）

CREATE MATERIALIZED VIEW base.v_period_payments AS
SELECT DISTINCT
dp.card_id,
dp.year, 
dp.month, 
dp.debt_amount, 
string_agg(to_char(p.payment_date, 'DD.MM.YYYY'), ', ') OVER ( PARTITION BY p.period_id
ORDER BY payment_date
range between unbounded preceding  and unbounded following  -- used to aggregate full range
) AS 
pay_dates 
FROM base.debt_period dp
LEFT JOIN base.payments p on (p.period_id = dp.id)
WHERE dp.card_id = '№001137'   
ORDER BY dp.card_id

如何在＆＃34; string_agg＆＃34;中订购字符串用于窗口函数（postgresql）？

2 个答案: