爲什麼我的觸發器避免重複的行不起作用？

Question

在任何人建議一個唯一索引或密鑰之前，我有一個很好的例子。

我用這觸發，從Trigger to prevent Insertion for duplicate data of two columns：

CREATE TRIGGER LogDuplicates ON bkPersonPoints 
FOR INSERT 
AS 
if exists (select * from bkPersonPoints c 
        inner join inserted i 
         on c.Name = i.Name and c.Points = i.Points) 
begin 
    rollback 
end 
GO 

這個答案被接受，並且具有15升的投票，所以我希望它的工作，但即使在我的第一個刀片，成空表：

insert bkPersonPoints (Name, Points) values ('Brady', 100) 

我得到的錯誤：

The transaction ended in the trigger. The batch has been aborted.

附錄：該表看起來是這樣的：

CREATE TABLE [dbo].[bkPersonPoints](
    [Id] [int] IDENTITY(1,1) NOT NULL, 
    [Name] [nvarchar](50) NOT NULL, 
    [Points] [int] NOT NULL 
) ON [APP_BR2_User] 

Answer 1

發生這種情況，因爲它檢測您當前插入到表中的記錄。你需要篩選出EXISTS條款：反正

CREATE TRIGGER LogDuplicates ON bkPersonPoints 
FOR INSERT 
AS 
if exists (select * from bkPersonPoints c 
        inner join inserted i 
         on c.Name = i.Name 
         and c.Points = i.Points 
         and c.id <> i.id) 
begin 
    rollback 
end 
GO 

Answer 2

，建議約束

ALTER TABLE bkPersonPoints 
    ADD CONSTRAINT c_uniq_Name_and_points UNIQUE (Name, Points)