If statement - TSQL - sql-server

Question

What I'm trying to achieve is to check if a table exists:
if it exists, just truncate it
if it does not exist, create the table
Below is my code but I get an error.
Code:
--Check if table exists
IF EXISTS (SELECT * FROM sys.objects
WHERE object_id = OBJECT_ID(N'[dbo].[Com_SQL_Server_Agent_Monitor]')
AND type in (N'U'))
TRUNCATE TABLE [dbo].[Com_SQL_Server_Agent_Monitor]
ELSE
--Create table if not exist
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Com_SQL_Server_Agent_Monitor]
(
[job_id] [uniqueidentifier] NULL,
[originating_server] [nvarchar](30) NULL,
[name] [nvarchar](128) NULL,
[enabled] [tinyint] NULL,
[description] [nvarchar](512) NULL,
[start_step_id] [int] NULL,
[category] [nvarchar](128) NULL,
[owner] [nvarchar](128) NULL,
[notify_level_eventlog] [int] NULL,
[notify_level_email] [int] NULL,
[notify_level_netsend] [int] NULL,
[notify_level_page] [int] NULL,
[notify_email_operator] [nvarchar](128) NULL,
[notify_netsend_operator] [nvarchar](128) NULL,
[notify_page_operator] [nvarchar](128) NULL,
[delete_level] [int] NULL,
[date_created] [datetime] NULL,
[date_modified] [datetime] NULL,
[version_number] [int] NULL,
[last_run_date] [int] NULL,
[last_run_time] [int] NULL,
[last_run_outcome] [int] NULL,
[next_run_date] [int] NULL,
[next_run_time] [int] NULL,
[next_run_schedule_id] [int] NULL,
[current_execution_status] [int] NULL,
[current_execution_step] [nvarchar](128) NULL,
[current_retry_attempt] [int] NULL,
[has_step] [int] NULL,
[has_schedule] [int] NULL,
[has_target] [int] NULL,
[type] [int] NULL
) ON [PRIMARY]
GO
This is the error I get:
There is already an object named 'Com_SQL_Server_Agent_Monitor' in the database
Any ideas what I'm missing?

Answer 1

The biggest problem in your code is the fact that you have multiple SQL statements in your ELSE block - but they're not framed by a BEGIN ... END.
So really what you have right now is:
IF EXISTS (....)
TRUNCATE TABLE [dbo].[Com_SQL_Server_Agent_Monitor]
ELSE
SET ANSI_NULLS ON
-- these statements will be executed ALWAYS - no matter what the
-- IF EXISTS() check returns!
SET QUOTED_IDENTIFIER ON
GO
CREATE TABLE [dbo].[Com_SQL_Server_Agent_Monitor]
......
So even if the table exists, and gets truncated - the SET QUOTED_IDENTIFIER ON and the CREATE TABLE statement will still be executed! That's why you're getting an error "table already exists".
What you need to do is:
IF EXISTS (....)
TRUNCATE TABLE [dbo].[Com_SQL_Server_Agent_Monitor]
ELSE
BEGIN
SET ANSI_NULLS ON
SET QUOTED_IDENTIFIER ON
CREATE TABLE [dbo].[Com_SQL_Server_Agent_Monitor]
......
END