c# - 为什么我的 SQL 查询返回重复的结果？

Question

SQL 如下 - 每个结果出现 3 次而不是一次。

SELECT Consignments.LegacyID, TripDate, CollectionName, DeliveryName, Pallets, Weight, BaseRate, Consignments.FuelSurcharge, AdditionalCharges, BaseRate * Quantity AS 'InvoiceValue', Consignments.Customer, InvoiceNumber,
       CASE
          WHEN child.LegacyID = Consignments.Customer THEN child.LegacyID
          WHEN parent.LegacyID = Consignments.Customer THEN parent.LegacyID
          ELSE this.LegacyID
       END AS 'InvoiceAcc'
FROM SageAccount this
  LEFT JOIN SageAccount parent on parent.LegacyID = this.InvoiceAccount
  LEFT JOIN SageAccount child on this.LegacyID = child.InvoiceAccount
  JOIN Consignments on (Consignments.Customer = this.LegacyID AND this.Customer = 'True')
                    OR (Consignments.Customer = parent.LegacyID AND parent.Customer = 'True')
                    OR (Consignments.Customer = child.LegacyID AND child.Customer = 'True')
WHERE (this.LegacyID = @Customer) AND (TripDate BETWEEN @fromdate AND @todate) AND (InvoiceNumber IS NOT NULL)

SQL 是为另一个类似的查询提供给我的，但这次我修改了它以尝试将它用于我现在正在做的查询，所以我假设我在做一些愚蠢的事情。

非常感谢。

Answer 1

可能是因为您的左联接每个父行有 3 个子行。做一个 select * 来查看你的结果在相乘的行中有什么不同。