Question

我有这个触发器将列值合并到其父表。在这种情况下，InvoiceTotal被添加/减去帐户的InvoiceTotal

WITH Deltas as (
    SELECT AccountID, Sum(InvoiceTotal) as InvoiceTotal From inserted Group By AccountID
    UNION ALL
    SELECT AccountID, Sum(InvoiceTotal * -1) as InvoiceTotal From deleted Group By AccountID
),
Merged as
    (Select AccountID, Sum(InvoiceTotal) InvoiceTotal From Deltas Group by AccountID)
Update Account set InvoiceTotal = Account.InvoiceTotal + Merged.InvoiceTotal From Merged Where Account.AccountID = Merged.AccountID;

现在我在发票表中有一个名为IsCancelled的新列。如何修改上面的触发器来处理？如果取消发票，则帐户总数应减少，如果IsCancelled设置为0，则应增加。

是否可以在一个SQL语句中执行上述任务？

由于

Answer 1

WITH Deltas as (
    SELECT AccountID, CASE WHEN IsCancelled=0 THEN Sum(InvoiceTotal) ELSE Sum(InvoiceTotal*-1) END as InvoiceTotal From inserted Group By AccountID
    UNION ALL
    SELECT AccountID, CASE WHEN IsCancelled=0 THEN Sum(InvoiceTotal*-1) ELSE Sum(InvoiceTotal) END  as InvoiceTotal From deleted Group By AccountID
),
Merged as
    (Select AccountID, Sum(InvoiceTotal) InvoiceTotal From Deltas Group by AccountID)
Update Account set InvoiceTotal = Account.InvoiceTotal + Merged.InvoiceTotal From Merged Where Account.AccountID = Merged.AccountID;

条件可能会对此有所帮助。

更新已删除的部分。

Answer 2

我认为使用Indexed视图而不是触发器以获得发票的总价更好。我建议你有以下索引视图：

CREATE VIEW vw_InvoiceTotal With SCHEMABINDING 
AS 
    SELECT AccountId, 
             SUM (CASE WHEN IsCancelled=0 THEN InvoiceTotal ELSE -InvoiceTotal END) as InvoiceTotal,
             Count_Big(*) AS c
    FROM Deltas 
    GROUP By AccountId
End


CREATE UNIQUE CLUSTERED INDEX PK_InvoiceTotal ON dbo.vw_InvoiceTotal (AccountId)

通过这种方式，SQL Server可以通过表上的内部触发器自动同步索引视图。并且您可以将此视图用于以上性能。

SELECT * FROM vw_InvoiceTotal WITH(NOEXPAND)

如果你需要在你的mastertable中有InvoiceTotal列，我建议你有以上索引视图并在Deltas表上有以下触发器：

Create Trigger tr_sync_deltas on dbo.deltas
AFTER INSERT, UPDATE, DELETE
AS Begin
    Update MasterTable
    Set InvoiceTotal = ISNULL(i.InvoiceTotal,0)
    From (
       Select AccountId From Inserted
       Union
       Select AccountId From deleted
       )z
    Left Join dbo.vw_InvoiceTotal i on i.AccountId = z.AccountId
    Where MasterTable.AccountId = z.AccountId
End

Answer 3

是的，我相信通过使用带有WHEN MATCHED / NOT MATCHED结构的MERGE可以在SQL Server上实现，您可以根据需要添加任意数量的AND条件。

具体请参阅Microsoft在MERGE上的参考，参见示例B. 使用MERGE在单个语句中对表执行UPDATE和DELETE操作

我没有在我的回复中粘贴它，因为我现在没时间重新考虑这个例子以符合您的情况，我会尝试。无论哪种方式，这应该可以满足您的需求。

Answer 4

通过将IsCancelled标记添加到发票表中，您说当取消发票时，您希望从帐户余额中删除该发票总金额。另一种说法是，当IsCancelled = 1时，InvoiceTotal应被视为0，并相应地更新帐户余额。例如：如果旧发票总额为100，然后取消该发票，则应从帐户表中减去100（插入/新值0减去已删除/旧值为100）。在这种情况下，您可以按如下方式更新触发器查询。

WITH Deltas as (
    SELECT AccountID, Sum(case when IsCancelled = 0 then InvoiceTotal else 0 end) as InvoiceTotal From inserted Group By AccountID
    UNION ALL
    SELECT AccountID, Sum(case when IsCancelled = 0 then InvoiceTotal * -1 else 0 end) as InvoiceTotal From deleted Group By AccountID
),
Merged as
    (Select AccountID, Sum(InvoiceTotal) InvoiceTotal From Deltas Group by AccountID)
Update Account set InvoiceTotal = Account.InvoiceTotal + Merged.InvoiceTotal From Merged Where Account.AccountID = Merged.AccountID;

这是一个SQL小提琴，其中包含了这个实例。 http://sqlfiddle.com/#!6/e0246/16

用于将总计合并到父表的SQL触发器（带有已取消的列）

4 个答案: