DELETE的MSsql触发器

Question

我想让触发器阻止员工从角色表中删除，如果该员工已经在处理任务。如果任务尚未开始，则应该可以从角色表中删除员工。

触发：

CREATE TRIGGER trg_role_del 
ON Role 
FOR DELETE AS 

IF EXISTS (SELECT Task.StartTask, Role.EmployeeId, 
FROM Task, Role, deleted 
WHERE Role.EmployeeId = deleted.EmployeeId 
AND Role.EmployeeId = Task.EmployeeId 
AND GETDATE() > Task.StartTask) 
BEGIN 
    RAISERROR ('This role is working on a task, cannot be removed', 16, 1) 
ROLLBACK TRANSACTION 
END; 

DELETE语句：

DELETE FROM Role 
WHERE EmplyeeId = '003' 

然而触发以上不起作用。所有删除都会经过，触发器不会停止任何操作。如果SELECT语句单独运行，它会从表中选择正确的值，所以SELECT看起来很好。我似乎无法让代码正常工作。帮助将不胜感激！

Answer 1

我会去的，而不是删除触发器：

CREATE TRIGGER trg_role_del 
ON Role 
INSTEAD OF DELETE AS 

DELETE r 
FROM Role r 
INNER JOIN deleted ON r.EmployeeId = deleted.EmployeeId 
LEFT JOIN Task ON r.EmployeeId = Task.EmployeeId 
       AND GETDATE() > Task.StartTask 
WHERE Task.Id IS NULL -- Any non-nullable column on the task table is good here 

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Answer 2

您创建了“AFTER DELETE”触发器，而您应创建“INSTEAD OF”触发器。