SQL 查询聚合可能不会出现在 WHERE 子句中

Question

我有这个 SQL 语句，SQL Server 给我以下错误:

An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING clause or a select list.

SELECT 
  SUM(M1.InvoiceTotal)-SUM(M1.AmountApplied) as PastDueAmount
  , M1.BillingID
  , M2.Name
  , M2.DelinquentDaysThreshold
  , M2.DelinquentAmountThreshold
  , DATEDIFF(d, MIN(BillingDate),GETDATE()) as DaysLate
FROM Invoices M1 
LEFT JOIN ClientAccounts M2 ON M1.BillingID = M2.ID
WHERE 
  InvoiceTotal <> AmountApplied
  AND M2.DelinquentDaysThreshold > DATEDIFF(d, MIN(BillingDate),GETDATE())
  OR (SUM(M1.InvoiceTotal)-SUM(M1.AmountApplied)) > M2.DelinquentAmountThreshold
GROUP BY 
  M1.BillingID
  , M2.Name
  , M2.DelinquentDaysThreshold
  , M2.DelinquentAmountThreshold

在 where 子句中，我只想提取最早的未付帐单发票日期大于 DelinquentDaysThreshhold(以天为单位)或 PastDueAmount(计算值)大于 DelinquentAmountThreshold 的记录。
由于某种原因，SQL Server 不喜欢聚合金额。

Answer 1

按照错误消息提示使用HAVING，这需要GROUP BY:

SELECT
    SUM(M1.InvoiceTotal)-SUM(M1.AmountApplied) as PastDueAmount, 
    M1.BillingID, M2.Name, 
    M2.DelinquentDaysThreshold, M2.DelinquentAmountThreshold,
    DATEDIFF(d, MIN(BillingDate),GETDATE()) as DaysLate
FROM
    Invoices M1
    LEFT JOIN
    ClientAccounts M2 ON M1.BillingID = M2.ID
WHERE
    InvoiceTotal <> AmountApplied
    AND
    M2.DelinquentDaysThreshold > DATEDIFF(d, MIN(BillingDate),GETDATE())
GROUP BY
    M1.BillingID, M2.Name, 
    M2.DelinquentDaysThreshold, M2.DelinquentAmountThreshold,
    DATEDIFF(d, MIN(BillingDate),GETDATE())
HAVING
    (SUM(M1.InvoiceTotal)-SUM(M1.AmountApplied)) > M2.DelinquentAmountThreshold