sql - PostgreSQL 8.4 : Summation by account numbers

Question

我正在做一些关于财务账户的报告，我需要根据初始数字对各个级别的值求和... 例如，对以 0(01、011、012..)或 1(1、10、111...)或 111(111,1112,1113...)开头的帐户的所有值求和等.

这是简化的示例表:

CREATE TABLE account(id, acctNo, credit) AS (
    VALUES
       (1, '01', 100)
      ,(2, '011', 200)
      ,(3, '0112', 300)
      ,(4, '014', 400)
      ,(5, '0144', 500)
      ,(6, '0148', 600)
      ,(7, '01120', 100)
      ,(8, '01121', 100)
      ,(9, '0140', 50)
      ,(10,'02', 50)
      ,(11,'021', 50)
      ,(12,'1', 50)
      ,(13,'10', 100)
      ,(15,'100', 50)    
      ,(14,'1021', 50)
      ,(16,'202', 50)
      ,(17,'221', 50)
      ,(18,'4480', 50)
      ,(19,'447', 50)
      ,(20,'5880', 50)
    )

我设法做到了，但它是一种健壮的 SQL，有没有更好的解决方案？ 这是代码:

WITH
    a AS (SELECT SUBSTRING(acctNo,1,1) AS LEVEL,
    SUM(credit)  AS sum1 FROM account GROUP BY LEVEL
    ORDER BY LEVEL),
    b AS
   (SELECT SUBSTRING(acctNo,1,2) AS level2,
    SUM(credit) FROM account GROUP BY level2
    ORDER BY level2),
        c AS
   (SELECT SUBSTRING(acctNo,1,3) AS level3,
    SUM(credit) FROM account GROUP BY level3
    ORDER BY level3),
    d AS (SELECT SUBSTRING(acctNo,1,4) AS level4,
    SUM(credit) FROM account GROUP BY level4
    ORDER BY level4),
     e AS (SELECT SUBSTRING(acctNo,1,5) AS level5,
    SUM(credit) FROM account GROUP BY level5
    ORDER BY level5)

 SELECT * FROM
 (SELECT a.* FROM a
 UNION (SELECT b.* FROM b WHERE char_length(level2)>=2)
 UNION (SELECT c.* FROM c WHERE char_length(level3)>=3)
 UNION (SELECT d.* FROM d WHERE char_length(level4)>=4)
 UNION (SELECT e.* FROM e WHERE char_length(level5)>=5)) a
 ORDER BY LEVEL

这仅适用于 5 个级别(五位数字)...是否有一些通用的解决方案？如果明天我需要 6 个级别，等等...

这里是 SQL Fiddle

谢谢。

Answer 1

耶 generate_series!

SELECT substring(a.acctNo from 1 for g.g) as level, sum(a.credit)    
FROM account a, generate_series(1,5) g
where length(a.acctNo) >= g.g
group by 1
order by 1