Question

如果该员工已经在处理任务，我希望触发器能够阻止从Role-table中删除员工。如果任务尚未启动，则应该能够从角色表中删除该员工。

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;

删除声明：

DELETE FROM Role
WHERE EmplyeeId = '003'

但是上面的触发器不起作用。所有删除都会通过，触发器不会停止任何操作。如果SELECT语句本身单独运行，它会从表中选择正确的值，因此SELECT似乎很好。我似乎无法使代码正常工作。非常感谢帮助！

Answer 1

我会使用而不是删除触发器：

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

你创建了一个“AFTER DELETE”触发器，你应该创建一个“INSTEAD OF”触发器。

用于DELETE的MSsql触发器

2 个答案: