Question

我是postgres的新手，我有一个令人不安的问题。假设我的SQL查询的输出是

123456789;"2014-11-20 12:30:35.454875";500;200;"2014-11-16 16:16:26.976258";300
123456789;"2014-11-20 12:30:35.454875";500;200;"2014-11-16 16:16:27.173523";100

我想要的是总结所有第4列，以便第一行包含第4列的总和

123456789;"2014-11-20 12:30:35.454875";500;400;"2014-11-16 16:16:26.976258";300

我的查询是

select l.phone_no, l.loan_time, l.cents_loaned/100, r.cents_deducted/100, r.event_time, 
r.cents_balance/100
from tbl_table1 l
LEFT JOIN tbl_table2 r
ON l.tb1_id = r.tbl2_id
where l.phone_no=123456789
order by r.event_time desc

任何帮助将不胜感激。

Answer 1

在整个集合（OVER ()）上使用window function作为框架：

select l.phone_no, l.loan_time, l.cents_loaned/100
     , sum(r.cents_deducted) OVER () / 100 AS total_cents_deducted
     , r.event_time, r.cents_balance/100
FROM   tbl_table1 l
LEFT   JOIN tbl_table2 r ON l.tb1_id = r.tbl2_id
WHERE  l.phone_no = 123456789
ORDER  BY r.event_time desc

这将返回所有行，而不仅仅是第一行。你的问题不清楚。

Answer 2

也许这有帮助。它将添加一个包含第4列总和的新行。

WITH query AS (
  SELECT l.phone_no, l.loan_time, l.cents_loaned/100 AS cents_loaned, 
         r.cents_deducted/100 AS cents_deducted, r.event_time, 
         r.cents_balance/100 AS cents_balance,
         ROW_NUMBER() OVER (ORDER BY r.event_time DESC) rn,
         SUM(cents_deducted/100) OVER () AS sum_cents_deducted
    FROM tbl_table1 l
    LEFT 
    JOIN tbl_table2 r
      ON l.tb1_id = r.tbl2_id
   WHERE l.phone_no=123456789
)
SELECT phone_no, loan_time, cents_loaned, cents_deducted, event_time, cents_balance
  FROM query
 WHERE rn > 1
 UNION
   ALL 
SELECT phone_no, loan_time, cents_loaned, sum_cents_deducted, event_time, cents_balance
  FROM query
 WHERE rn = 1

Postgres：在第一行中创建列包含其他行中相同列的总和

2 个答案: