sql-server-2008-r2 - 防止删除表的所有行

Question

有没有办法防止删除表中的所有行？我知道如何使用 DDL 触发器来防止删除表或截断。我曾经没有突出显示整个命令，省略了 where 子句，并删除了表中的所有行。除非存在 where 子句，否则我想防止这种情况再次发生。

Answer 1

你可以用触发器来做到这一点。

CREATE TRIGGER dbo.KeepRows
ON dbo.TableName
FOR DELETE
AS
BEGIN
  SET NOCOUNT ON;

  IF NOT EXISTS (SELECT 1 FROM dbo.TableName)
  BEGIN
    RAISERROR('Naughty developer, you tried to delete the last row!', 11, 1);
    ROLLBACK TRANSACTION;
  END
END
GO

为了避免删除然后回滚，如果表很大，这可能会非常昂贵，您可以将其实现为代替触发器，这将阻止任何工作发生（当然检查除外）。这假设该列id是主键：

CREATE TRIGGER dbo.KeepRows2
ON dbo.TableName
INSTEAD OF DELETE
AS
BEGIN
  SET NOCOUNT ON;

  IF EXISTS (SELECT 1 FROM dbo.TableName WHERE id NOT IN (SELECT id FROM deleted))
  BEGIN
    DELETE dbo.TableName WHERE id IN (SELECT id FROM deleted);
  END
  -- optional:
  ELSE
  BEGIN
    RAISERROR('Nice try, you need a WHERE clause!', 11, 1);
  END
END
GO