SQL Join Sum表不同于单一查询

Question

我的问题是：我有 3 tables Invoiced、Expired、Payed，每个 table 都有这些列：

customer_code
类型
数量

在 Oracle 中，我正在尝试这样做：

SELECT
    C.customer_code,
    C.type,
    SUM(C.AMOUNT)  AS AMOUNT_EXPIRED,
    SUM(F.AMOUNT)  AS AMOUNT_INVOICED,
    SUM(R.AMOUNT)  AS AMOUNT_PAYED        
  FROM Expired C
  LEFT JOIN (SELECT customer_code, ACCOUNT, SUM(AMOUNT) AS AMOUNT
               FROM Invoiced
              GROUP BY customer_code, type) F
    ON C.customer_code = F.customer_code
   AND C.type = F.type
LEFT JOIN (SELECT customer_code, type, SUM(AMOUNT) AS AMOUNT
             FROM Payed
            GROUP BY customer_code, type) R
    ON C.customer_code = R.customer_code
   AND C.type = R.type
 GROUP BY C.customer_code, C.type,
          R.customer_code, R.type, 
          F.customer_code, F.type

我得到一个 table 列：

------------------------------------------------------------------------
 customer_code | type | amount_expired | amount invoiced | amount payed
------------------------------------------------------------------------

但金额与单个查询不同：

SELECT customer_code, type, SUM(AMOUNT) AS AMOUNT FROM expired GROUP BY customer_code, type
SELECT customer_code, type, SUM(AMOUNT) AS AMOUNT FROM invoiced GROUP BY customer_code, type
SELECT customer_code, type, SUM(AMOUNT) AS AMOUNT FROM payed GROUP BY customer_code, type

谁能帮帮我？

Answer 1

使用 union 而不是 join。但是你应该有一个 table 来存储所有的客户代码和类型。当涉及聚合函数时，你永远不应该使用 join 。它非常混乱，通常会产生不正确的结果。

with CUSTOMER as (
    select CUSTOMER_CODE, TYPE from EXPIRED group by CUSTOMER_CODE, TYPE
    union 
    select CUSTOMER_CODE, TYPE from INVOICED group by CUSTOMER_CODE, TYPE
    union 
    select CUSTOMER_CODE, TYPE from PAYED group by CUSTOMER_CODE, TYPE
)
select
    c.CUSTOMER_CODE, c.TYPE
    ,(
    select sum(AMOUNT) 
    from EXPIRED 
    where CUSTOMER_CODE = c.CUSTOMER_CODE and TYPE = c.TYPE
    ) as AMOUNT_EXPIRED
    ,(
    select sum(AMOUNT) 
    from INVOICED 
    where CUSTOMER_CODE = c.CUSTOMER_CODE and TYPE = c.TYPE
    ) as AMOUNT_INVOICED
    ,(
    select sum(AMOUNT) 
    from PAYED 
    where CUSTOMER_CODE = c.CUSTOMER_CODE and TYPE = c.TYPE
    ) as AMOUNT_EXPIRED
from CUSTOMER c
order by c.CUSTOMER_CODE, c.TYPE

Answer 2

可能是你的第二个子查询的原因，这可能是你所期望的；

SELECT  C.customer_code, C.type, 
    SUM(C.AMOUNT)       AS AMOUNT_EXPIRED,
    SUM(F.AMOUNT)       AS AMOUNT_INVOICED,
    SUM(R.AMOUNT)       AS AMOUNT_PAYED        
FROM      Expired C
LEFT JOIN invoiced F
ON        C.customer_code= F.customer_code
AND       C.type= F.type
LEFT JOIN payed R 
ON        C.customer_code= R.customer_code
AND       C.type= R.type

GROUP BY  C.customer_code, C.type

SQL Join Sum表不同于单一查询

SQL Join Sum tables different from single queries

sql

oracle

subquery

left-join