Question

我有这张桌子：

CREATE TABLE Workspaces (
AreaNr CHAR(2)
    CONSTRAINT ck_a_areanr REFERENCES Areas(AreaNr)
    ON DELETE CASCADE
    ON UPDATE NO ACTION,
SpaceNr INT
    CONSTRAINT ck_spacenr CHECK (SpaceNr > 0 AND SpaceNr < 1001),
Area DECIMAL(2,1)
    CONSTRAINT ck_areal CHECK (area > 0),
CONSTRAINT ck_workspaces PRIMARY KEY (AreaNr, SpaceNr)
)

现在我想创建一个触发器，阻止从表Workspaces中删除单个行（随机选择）。目前我有以下触发器，但此触发器仍允许删除单行。

当前触发器：

CREATE TRIGGER deleteWorkspace ON Workspaces
FOR DELETE AS

BEGIN
DECLARE @Count int
SET @Count = @@ROWCOUNT;

IF @Count >= (SELECT SUM(row_count)
FROM sys.dm_db_partition_stats
WHERE OBJECT_ID = OBJECT_ID('Workspaces') AND index_id = 1
)

BEGIN
RAISERROR('You cannot delete all rows from Workspaces!',16,1)
ROLLBACK TRANSACTION
RETURN;
END

END
GO

期望的结果：我希望能够防止删除上面表格中的单行，如果有人可以帮我修改上面的触发器，我会非常感激，这样就可以修复。有谁知道如何做到这一点？

Answer 1

您希望在此实例中使用已删除的虚拟表。我不完全确定为什么你只关心单个行删除，但这里是代码：

CREATE TRIGGER deleteWorkspace ON Workspaces
FOR DELETE AS

IF(SELECT COUNT(*) FROM deleted) = 1
BEGIN
RAISERROR('Single Delete Not Allowed!', 16, 1)
ROLLBACK
END
ELSE
RAISERROR('Multiple Rows Being Deleted, Allowed!', 16, 1)
BEGIN
END

END
GO

-Sean

使用触发器防止单行删除

1 个答案: