Question

我有一系列相关的表格。

TRANSACTION_TYPE
Transaction_ID（主要）
TRANSACTION_AMOUNT
Transaction_Type

交易
Transaction_ID（主要）
时间戳

购买
TRANSACTION_ID
的Item_ID Purchase_ID（主要）

物品
的Item_ID
CLIENT_ID

我需要根据时间戳和client_id

选择transaction_type行

我的查询如下：

SELECT 
    SUM(tt.Transaction_Amount)
FROM 
    ItemTracker_dbo.Transaction_Type tt
JOIN    
    ItemTracker_dbo.Transaction t
   ON
    tt.Transaction_ID = t.Transaction_ID
JOIN
    ItemTracker_dbo.Purchase p
   ON
    p.Transaction_ID = tt.Transaction_ID
JOIN
    ItemTracker_dbo.Item i
   ON
    i.Item_ID = p.Item_ID
WHERE
    t.TimeStamp >= $start AND t.TimeStamp <= $end
   AND
    tt.Transaction_Format IN ('cash', 'credit')
   AND
    i.Client_ID = $client_ID

问题：

如果客户在交易中购买了多个商品，则transaction_id将在Purchase表中包含多个行。因此，连接正在为transaction_id重复transaction_amount，该事务在购买时有多行。

有没有办法将UNIQUE应用于此次查询的购买行？

还有其他方法可以解决购买中的多行问题吗？

或者我是否需要重新评估数据库的架构？

如果有任何其他信息有用，请告诉我。

Answer 1

使用子查询。

SELECT SUM(tt.Transaction_Amount)
FROM ItemTracker_dbo.Transaction_Type tt
WHERE tt.Transaction_ID IN 
(SELECT t.Transaction_ID FROM
        ItemTracker_dbo.Transaction t
    JOIN
        ItemTracker_dbo.Purchase p
       ON
        p.Transaction_ID = t.Transaction_ID
    JOIN
        ItemTracker_dbo.Item i
       ON
        i.Item_ID = p.Item_ID
    WHERE
        t.TimeStamp >= $start AND t.TimeStamp <= $end
       AND
        tt.Transaction_Format IN ('cash', 'credit')
       AND
        i.Client_ID = $client_ID)

Answer 2

需要使用内部选择，如下所示：

select sum(tt.Transaction_Amount)
from ItemTracker_dbo.Transaction_Type tt
inner join ItemTracker_dbo.Transaction t ON tt.Transaction_ID = t.Transaction_ID
inner join
(select distinct(transaction_id) as transID
from Purchase as P
inner join Item as I on P.Item_ID = I.Item_ID
where I.Client_ID = $client_ID) blah
on t.Transaction_ID = blah.transID
t.TimeStamp >= $start AND t.TimeStamp <= $end
   AND
    tt.Transaction_Format IN ('cash', 'credit')

Answer 3

我认为你必须使用子查询 - 一个带有函数sum和一个带有DISTINCT的嵌套查询

SELECT SUM(Transaction_Amount) 
FROM (
   SELECT DISTINCT
       tt.Transaction_Amount, t.Transaction_ID
   FROM 
       ItemTracker_dbo.Transaction_Type tt
   JOIN    
       ItemTracker_dbo.Transaction t
      ON
       tt.Transaction_ID = t.Transaction_ID
   JOIN
       ItemTracker_dbo.Purchase p
      ON
       p.Transaction_ID = tt.Transaction_ID
   JOIN
       ItemTracker_dbo.Item i
      ON
       i.Item_ID = p.Item_ID
   WHERE
       t.TimeStamp >= $start AND t.TimeStamp <= $end
      AND
       tt.Transaction_Format IN ('cash', 'credit')
      AND
       i.Client_ID = $client_ID
) table

我希望我理解你的问题。如果没有，那么抱歉误会

Answer 4

您可以按Transaction_ID和Transaction_amount对结果进行分组，然后获取全局总和。

select sum(Transaction_amount) from
(select Transaction_ID, Transaction_amount
from [...]
group by Transaction_ID, Transaction_amount) a

[Mysql]：选择UNIQUE w / join

4 个答案: