Question

我从podetail表中得到以下查询，其中我计算了＆＃34;一个＆＃34;的平均价格。一次唯一的项目。我需要创建一个＆＃34; avgUnitCost＆＃34;的列表。有没有办法在子查询中使用这个现有查询来生成avgUnitCost列表？

SELECT  items.`itemName`,
        SUM(podetails.`qtyReceived`) AS qtyRcvd,
        SUM(podetails.`qtyReceived` * podetails.`unitCost`) AS totalUnitCost,
        SUM(podetails.`qtyReceived` * podetails.`unitCost`) / SUM(podetails.`qtyReceived`) AS avgUnitCost

FROM podetails, items, purchaseorders
WHERE purchaseorders.`poID` = podetails.`poID`
  AND podetails.`itemID` = items.`itemID`
  AND podetails.`itemID` = 3;>

Answer 1

您在此处缺少GROUP BY声明。不确定哪一列是准确的，但假设您应该按items.itemName分组

SELECT  items.`itemName`,
    SUM(podetails.`qtyReceived`) AS qtyRcvd,

    SUM(podetails.`qtyReceived` * podetails.`unitCost`) AS totalUnitCost,

    SUM(podetails.`qtyReceived` * podetails.`unitCost`) / SUM(podetails.`qtyReceived`) AS avgUnitCost

FROM podetails JOIN purchaseorders

ON
    purchaseorders.`poID` = podetails.`poID`
JOIN items

ON
    podetails.`itemID` = items.`itemID`

WHERE
    podetails.`itemID` = 3

GROUP BY items.`itemName`;

Answer 2

如果您希望avgUnitCost显示purchaseorders表格中所有项目的SELECT items.`itemName`, SUM(podetails.`qtyReceived`) AS qtyRcvd, SUM(podetails.`qtyReceived` * podetails.`unitCost`) AS totalUnitCost, SUM(podetails.`qtyReceived` * podetails.`unitCost`) / SUM(podetails.`qtyReceived`) AS avgUnitCost FROM podetails, items, purchaseorders WHERE purchaseorders.`poID` = podetails.`poID` AND podetails.`itemID` = items.`itemID` GROUP BY items.`itemID`;，则以下查询可能会对您有所帮助

GROUP BY

使用while (iterator.hasNext()) { String key = (String) iterator.next(); Iist value = (list)map.get(key); System.out.println("Key: "+ key+", Value: "+ value); }的这一小改动可能会为您提供预期的结果

MySQL的;迭代表并计算avgerage价格

2 个答案: