Question

此主题与我之前的Combine fields from different rows on condition相关。

我调整了从此线程获得的查询以满足其他一些要求。

SELECT 
    a.Date,
    a.orderid AS AZNr,
    a.Typ,
    ROUND(a.Fees, 2) AS Fees,
    ROUND(b.Shipping, 2) AS Shipping,
    ROUND(c.Price, 2) AS Price,
    d.DeliveryLand
FROM
    (SELECT 
        posteddate AS Date,
            transactiontype AS Typ,
            orderid,
            SUM(amount) AS Fees
    FROM
        report
    WHERE
        amounttype = 'ItemFees'
    GROUP BY orderid) a
        LEFT JOIN
    (SELECT 
        orderid, SUM(amount) AS Shipping
    FROM
        report
    WHERE
        amountdescription = 'Shipping'
    GROUP BY orderid) b ON a.orderid = b.orderid
        LEFT JOIN
    (SELECT 
        orderid, SUM(amount) AS Price
    FROM
        report
    WHERE
        amountdescription = 'Principal'
    GROUP BY orderid) c ON b.orderid = c.orderid
        LEFT JOIN
    (SELECT 
        DeliveryLand, ExternalOrderId
    FROM
        orders) d ON c.orderid = d.ExternalOrderId
ORDER BY Date DESC

我必须在最后一个表上执行LEFT JOIN才能获得DeliveryLand，但并非报告表中的每个项目都在orders-table中有一个条目。

在我做了一些计算之后，我发现这个查询没有返回所有条目。应该有25个条目＆＃34; typ＆＃34; =＆＃34;退款＆＃34;，但我只得到20个。某些订单可能包含其他订单（由orderid标识）可能没有的条目。

我做了另一个询问，总结了退款的费用，运费和价格：

SELECT 
    SUM(ROUND(a.Fees, 2)) AS Fees,
    SUM(ROUND(b.Shipping, 2)) AS Shipping,
    SUM(ROUND(c.Price, 2)) AS Price
FROM
    (SELECT 
        orderid, SUM(amount) AS Fees
    FROM
        report
    WHERE
        amounttype = 'ItemFees'
            AND transactiontype = 'Refund'
    GROUP BY orderid) a
        LEFT JOIN
    (SELECT 
        orderid, SUM(amount) AS Shipping
    FROM
        report
    WHERE
        amountdescription = 'Shipping'
            AND transactiontype = 'Refund'
    GROUP BY orderid) b ON a.orderid = b.orderid
        LEFT JOIN
    (SELECT 
        orderid, SUM(amount) AS Price
    FROM
        report
    WHERE
        amountdescription = 'Principal'
            AND transactiontype = 'Refund'
    GROUP BY orderid) c ON b.orderid = c.orderid

前两个结果，费用和运费，总结正确（我得到原始数据进行比较），但最后一个，价格，是不正确的，它太多了。我猜有些数据会被LEFT JOIN截断，但是我无法弄清楚原因和位置，尤其是当我总结相同的列时，＃34; transactiontype＆＃34 ; =＆＃34;订单＆＃34;。

我不知道为什么有些数据被截断或丢失。有人可以帮助我解决这两个问题中令人困惑的JOIN吗？如果您需要更多信息，请询问。

提前谢谢！

€dited query：

  SELECT 
    posteddate AS Date,
    transactiontype AS Typ,
    report.orderid AS AZNr,
    ROUND(SUM((amounttype = 'ItemFees') * amount),
            2) AS Fees,
    ROUND(SUM((amountdescription = 'Shipping') * amount),
            2) AS Shipping,
    ROUND(SUM((amountdescription = 'Principal') * amount),
            2) AS Price,
    orders.DeliveryLand,
    articles.ItemVAT AS VAT
FROM
    report
        LEFT JOIN
    orders ON report.orderid = orders.ExternalOrderID
        LEFT JOIN
    articles ON report.sku = articles.ItemID
GROUP BY report.orderid , transactiontype

Answer 1

我从简化查询开始，可以在没有JOIN的情况下编写。我还要问{1} ROUND之前SUM为何会花费更长时间并且不那么准确。

我做：

  SELECT orderid,
         ROUND(SUM((amountdescription='ItemFees')*amount), 2)) AS Fees,
         ROUND(SUM((amountdescription='Shipping')*amount), 2)) AS Shipping,
         ROUND(SUM((amountdescription='Principal')*amount), 2)) AS Price
    FROM report
   WHERE transactiontype='Refund'
GROUP BY orderid

作为解释(amountdescription='ItemFees')如果为真则返回1，如果不是则返回0，因此仅对与指定的每个条件匹配的金额进行求和..如果您愿意，可以使用更长的CASE：

SUM(CASE WHEN *condition* THEN amount ELSE 0 END)

您可能会丢失原始查询中的一些数据，因为它依赖于链接的所有子表..如果没有Fees则订单Shipping和{{1}不会被退回。

<强>更新

不要忘记，如果您在同一个orderid上有两个交易类型，它们都将被视为相同的订单，并且都将包含在相同的金额中......以分别使用交易类型：

Price

由JOIN混淆 - 结果中缺少数据

1 个答案: