How to add "IF NOT EXISTS" to create trigger statement

Question

I am using sql server 2008 R2. More specifically, Microsoft SQL Server 2008 R2 (RTM) - 10.50.1600.1 (X64) Apr 2 2010 15:48:46 Copyright (c) Microsoft Corporation Standard Edition (64-bit) on Windows NT 6.1 (Build 7601: Service Pack 1) (Hypervisor). I am new to sql server and procedures/triggers. I have the following code to create a trigger (it works):

CREATE TRIGGER [dbo].[Insert_WithdrawalCodes]     ON  [dbo].[PupilWithdrawalReason]     AFTER INSERT AS  BEGIN     SET NOCOUNT ON;         UPDATE [dbo].[PupilWithdrawalReason] SET DateCreated=dbo.SYSTEMTIME()          WHERE WithdrawalCodeID IN (SELECT WithdrawalCodeID FROM inserted) END 

How do I conditionally create only if the trigger does not yet exist? What am I doing wrong here? StackOverflow has good examples of IF NOT EXISTS, but I can't get this to work in conjunction with a CREATE. Here is one of my failed efforts:

IF NOT EXISTS (SELECT * FROM sys.objects WHERE type = 'TR' AND name = 'Insert_WithdrawalCodes')    exec('CREATE TRIGGER [dbo].[Insert_WithdrawalCodes] ON  [dbo].[PupilWithdrawalReason] AFTER INSERT AS BEGIN SET NOCOUNT ON; UPDATE [dbo].[PupilWithdrawalReason] SET DateCreated=dbo.SYSTEMTIME() WHERE WithdrawalCodeID IN (SELECT WithdrawalCodeID FROM inserted) END') GO 

Answer 1

IF EXISTS (SELECT * FROM sys.triggers WHERE object_id = OBJECT_ID(N'[dbo].[TRIGGERNAME]')) DROP TRIGGER [dbo].[TRIGGERNAME] go IF  EXISTS (SELECT * FROM dbo.sysobjects WHERE id = OBJECT_ID(N'[dbo].[TABLENAME]') AND OBJECTPROPERTY(id, N'IsUserTable') = 1) BEGIN CREATE   TRIGGER [dbo].[TRIGGERNAME] ON [dbo].[TABLENAME] FOR INSERT, UPDATE   AS ...  END 

Based on your updated question... try this:

IF NOT EXISTS (select * from sys.objects where type = 'TR' and name = 'Insert_WithdrawalCodes') EXEC dbo.sp_executesql @statement = N'  CREATE TRIGGER [dbo].[Insert_WithdrawalCodes]     ON  [dbo].[PupilWithdrawalReason]     AFTER INSERT AS  BEGIN     SET NOCOUNT ON;         UPDATE [dbo].[PupilWithdrawalReason] SET DateCreated=dbo.SYSTEMTIME()          WHERE WithdrawalCodeID IN (SELECT WithdrawalCodeID FROM inserted) END    ' 

Answer 2

The best way is to check for objects and drop them if they exist before you create them.

Rather then not creating it at all if it exists, I would approach it the other way, drop it if exists and then create.

Normally in long lenghty scripts if you want to update the definition of a trigger you would just simply add this at the end of that script and your trigger definition will be updated.

So the approach should be create the object but drop it if it already exists rather then dont create it at all if it already exists

IF OBJECT_ID ('[Insert_WithdrawalCodes] ', 'TR') IS NOT NULL    DROP TRIGGER [Insert_WithdrawalCodes]; GO  CREATE TRIGGER .......