Sql server 插入更新后的SQL触发器

这个代码有什么问题

如果我像这样打字

Declare tmp as CURSOR FOR
Select i.ID from Inserted
OPEN tmp 

或者如果我打字

Declare tmp as CURSOR FOR
Select i.ID from Deleted
OPEN tmp 

很有魅力但是

我有没有办法写这样的东西

if @operation <> 3

set @tmp = 'SELECT i.id FROM inserted i '

 else

 set @tmp =' SELECT i.id FROM deleted i '

 DECLARE tmpUpit CURSOR FOR 
@tmp
 OPEN tmpUpit 

---

我需要根据插入/更新/删除的状态将值从一个表插入到另一个表中，这是完全未测试的，因为发布的表结构与发布的触发代码不匹配。这至少应该说明，您可以将其重新考虑为基于集合的逻辑，而不是一行一行地折磨人

CREATE TRIGGER [dbo].[Trigger212] ON [dbo].[Towns]  
FOR INSERT, UPDATE, DELETE AS
BEGIN 
    SET NOCOUNT ON;

    DECLARE @operation int
    DECLARE @Variable1 nvarchar(8) = 'Woof'
    DECLARE @Variable2 nvarchar(4) = 'Foof'

    --Capture the Operation (Inserted, Deleted Or Updated) 
    IF EXISTS(SELECT * FROM inserted) AND NOT EXISTS (SELECT * FROM deleted)
        SET @operation = 1 --Insert
    ELSE
        IF EXISTS(SELECT * FROM inserted) AND EXISTS (SELECT * FROM deleted)
            SET @operation = 2 --update
        ELSE
            SET @operation = 3 -- DELETE

    INSERT Requests
    (
        Field1
        , Field2
        , ID
        , TableName
        , Operation
        , TimeU
        , Status
    )
    SELECT 'Woof'
        , 'Foof'
        , i.ID
        , 'Towns'
        , @operation
        , GETDATE()
        , 0
    FROM inserted i
    LEFT JOIN Requests r on r.ID = i.ID
        AND r.Operation = 3
            OR (r.Operation = 1 and r.ID = i.ID)
        AND r.Status = 0
        AND r.TableName = 'Towns'
    WHERE r.ID IS NULL

    DELETE r
    FROM Requests r
    JOIN inserted i on i.Field1 = r.Field1
        AND i.Field2 = r.Field2
        AND i.ID = r.ID
        AND i.Operation <> @operation
    WHERE r.TableName = 'Towns'
        AND r.Status = 0   
END 

---

总的来说，我认为应该避免触发器，但它们有它们的位置。当触发器合适时，我通常不太喜欢做这三个操作。随着时间的推移，它变得非常混乱，因为您总是需要为不同的操作执行不同的逻辑。将它们拆分为三个触发器可以大大减少维护的痛苦。

为什么您首先需要光标？它们效率极低。您尝试的方法将不起作用，因为您已经进入动态sql领域。如果您可以发布一些关于触发器试图执行的操作的详细信息，我们可以帮助您找到一种不需要光标的基于集合的方法。@SeanLange我刚刚点击了编辑。。这是我的第一次trigger@myString，您可以有条件地声明它，甚至可以将游标变量作为参数传递给SP。您不需要动态sql。但不知何故，我假设您需要完全连接。在任何情况下，您都不希望在触发器中放置游标。从不这很容易以基于集合的方式完成，而且代码行也会更少。这里完全不需要光标。这是两个基本语句，一个insert和一个delete。但是我不能提供太多，因为你没有提供全部的触发。光标之外还有一些额外的标量值。游标中的标量值是一个巨大的红旗，表示内容不基于设置，无法处理多行操作。发布mytable的ddl以及该触发器附加到的任何表，我可以帮助您解决这个问题。

CREATE TRIGGER [dbo].[Trigger212] ON [dbo].[Towns]  
FOR INSERT, UPDATE, DELETE AS
BEGIN 
    SET NOCOUNT ON;

    DECLARE @operation int
    DECLARE @Variable1 nvarchar(8) = 'Woof'
    DECLARE @Variable2 nvarchar(4) = 'Foof'

    --Capture the Operation (Inserted, Deleted Or Updated) 
    IF EXISTS(SELECT * FROM inserted) AND NOT EXISTS (SELECT * FROM deleted)
        SET @operation = 1 --Insert
    ELSE
        IF EXISTS(SELECT * FROM inserted) AND EXISTS (SELECT * FROM deleted)
            SET @operation = 2 --update
        ELSE
            SET @operation = 3 -- DELETE

    INSERT Requests
    (
        Field1
        , Field2
        , ID
        , TableName
        , Operation
        , TimeU
        , Status
    )
    SELECT 'Woof'
        , 'Foof'
        , i.ID
        , 'Towns'
        , @operation
        , GETDATE()
        , 0
    FROM inserted i
    LEFT JOIN Requests r on r.ID = i.ID
        AND r.Operation = 3
            OR (r.Operation = 1 and r.ID = i.ID)
        AND r.Status = 0
        AND r.TableName = 'Towns'
    WHERE r.ID IS NULL

    DELETE r
    FROM Requests r
    JOIN inserted i on i.Field1 = r.Field1
        AND i.Field2 = r.Field2
        AND i.ID = r.ID
        AND i.Operation <> @operation
    WHERE r.TableName = 'Towns'
        AND r.Status = 0   
END