July 30, 2013 at 6:24 am
I'm a newbie at SQL, so please go easy, LOL. I have an SQL Express 2008 R2 database that contains 2 tables, one called StudentID and the other called StaffID. These tables are used by a third party software. I have created the following AFTER INSERT trigger for both tables that creates the next barcode values. The trigger in the StudentID table fires every time a record is inserted, but the trigger in the StaffID will fire once and then stop firing after SQL server restart. I can't understand why this is happening since the triggers are same just in 2 different tables.
USE [GroupTables]
GO
/****** Object: Trigger [dbo].[AddBarCode] Script Date: 07/15/2013 08:29:07 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author:<Tager, Kevin>
-- Create date: <7/13/2013>
-- Description:<Trigger to generate next barcode values on insert>
-- =============================================
CREATE TRIGGER [dbo].[AddBarCode]
ON [dbo].[StudentID]
AFTER INSERT
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
-- Update the barcode numbers of the most recently Inserted Record
UPDATE [dbo].[StudentID]
SET [FoodBarcode] = [dbo].[StudentID].[AI] + 3289,
[LibraryBarcode] = [dbo].[StudentID].[AI] + 880101800707
WHERE [dbo].[StudentID].[AI] = @@Identity
END
GO
July 30, 2013 at 6:28 am
your trigger is very close;
inside a trigger, isntead of using @@identity, you wnat to use the virtual tables INSERTED (or DELETED, where approriate);
that virtual table allows oyu to handle multiple rows at teh same time, and already has teh new values generated from any identity() columns, calculated columns, etc.
USE [GroupTables]
GO
/****** Object: Trigger [dbo].[AddBarCode] Script Date: 07/15/2013 08:29:07 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
-- =============================================
-- Author: <Tager, Kevin>
-- Create date: <7/13/2013>
-- Description:<Trigger to generate next barcode values on insert>
-- =============================================
CREATE TRIGGER [dbo].[AddBarCode]
ON [dbo].[StudentID]
AFTER INSERT
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
-- Update the barcode numbers of the most recently Inserted Record
UPDATE [dbo].[StudentID]
SET [FoodBarcode] = [dbo].[StudentID].[AI] + 3289,
[LibraryBarcode] = [dbo].[StudentID].[AI] + 880101800707
FROM INSERTED --INSERTED and DELETED are virtual tables, inside a trigger, with the new/old values
WHERE [dbo].[StudentID].[AI]= INSERTED.[AI] --[AI] is the identity of the table/PK
END
GO
Lowell
July 30, 2013 at 6:46 am
Lowell,
Thanks for the reply. Since I"m knew to SQL, I'm unfamiliar with how to work worth the inserted table. How would I modify my code to use it? I"m still unclear as to why the trigger, the way I wrote it, isn't firing on the one table, but is on the other. Any reason why it wouldn't fire?
July 30, 2013 at 6:47 am
Lowell,
Sorry, didn't see your inserted code? Would using the INSERTED table get the trigger to fire each time?
July 30, 2013 at 7:01 am
ktager (7/30/2013)
Lowell,Sorry, didn't see your inserted code? Would using the INSERTED table get the trigger to fire each time?
basically, we are updating the current table from INSERTED, so that we limit the affected rows to only those in teh update, and not every row in the table.
:
UPDATE [dbo].[StudentID]
SET [FoodBarcode] = [dbo].[StudentID].[AI] + 3289,
[LibraryBarcode] = [dbo].[StudentID].[AI] + 880101800707
FROM INSERTED --INSERTED and DELETED are virtual tables, inside a trigger, with the new/old values
WHERE [dbo].[StudentID].[AI]= INSERTED.[AI] --[AI] is the identity of the table/PK
Lowell
July 30, 2013 at 8:10 am
Lowell,
thanks, I will update the trigger to use the INSERTED table and retest to see if the trigger fires every time.
Kevin
July 30, 2013 at 10:04 am
ktager (7/30/2013)
Lowell,thanks, I will update the trigger to use the INSERTED table and retest to see if the trigger fires every time.
Kevin
the trigger always fires every time, it's just it might not update the data you expect it to.
Lowell
July 30, 2013 at 10:57 am
Lowell,
The problem I was having with the Staff table was that every time a record was added and saved, the 2 generated fields by the trigger were blank, which to me means the trigger wasn't firing.
I'm going to setup a test environment that hopefully duplicates my customers environment and see if I can duplicate the issue. If I can't, then I'm going to assume it must be an issue with the SQL 2008 express on their server.
thanks again for the help, much aprreciated.
Kevin
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