T-SQL Update Trigger - sql-server

Question

I'm trying to create the following trigger in SQL Server, but SSMS throws an error and I have no clue what it is. Any thoughts ?
Msg 156, Level 15, State 1, Line 2
Incorrect syntax near the keyword 'trigger'.
Code:
IF NOT EXISTS(SELECT * FROM sys.triggers
WHERE object_id = OBJECT_ID(N'[dbo].[trAfterUpdateInfoDoc]'))
CREATE TRIGGER [dbo].[trAfterUpdateInfoDoc]
ON [dbo].[InfoDocs]
AFTER UPDATE
AS
BEGIN
DECLARE #infodoctemplateid INT;
DECLARE #infodocid INT;
DECLARE #requireccount FLOAT(2);
DECLARE #filledcount FLOAT(2);
DECLARE #pcnt FLOAT(2);
DECLARE c CURSOR FOR
SELECT id
FROM InfoDocs ifd
WHERE exists (SELECT 1 FROM Inserted AS i WHERE i.id = ifd.id)
OPEN c
FETCH NEXT FROM c INTO #infodocid
WHILE ##Fetch_Status = 0
BEGIN
SELECT #infodoctemplateid = InfoDocTemplateId
FROM InfoDocs
WHERE id = #infodocid;
SELECT #requireccount = COUNT(*)
FROM InfoDocTemplateFields
WHERE InfoDocTemplateId = #infodoctemplateid
AND IsRequired = 1;
IF (#requireccount = 0)
BEGIN
set #pcnt = 100;
END
ELSE
BEGIN
select #filledcount = count(*) from InfoDocFields
where InfoDocId = #infodocid
and InfoDocTemplateFieldId in (select id from InfoDocTemplateFields where InfoDocTemplateId = #infodoctemplateid and IsRequired = 1)
and (BooleanValue is not null or (StringValue is not null and StringValue <> '') or IntValue is not null or DateValue is not null)
set #pcnt = #filledcount / #requireccount * 100.0;
END
update InfoDocs set PercentageCompleted = #pcnt Where id = #infodocid;
Fetch next From c into #infodocid
End
Close c
Deallocate c
END

Answer 1

Create Trigger (Limitations section) must be the first statement in a batch, so you can't use the IF exists check before it.
In SQL Server 2016 SP1 onwards, you can use CREATE OR ALTER TRIGGER... for the same behaviour.
Pre-SQL Server 2016 SP1, there's some suggestions here
I also second Zohar's comment that putting this logic into a trigger could well cause you many performance issues & possibly hard to track down unexpected behaviour/bugs.

Answer 2

Anytime a SQL object like a trigger is created, it needs to be the only object created in the batch. A batch is terminated by the keyword GO.
Try refactoring your code to fit this general structure and see if it works:
IF OBJECT_ID(N'[dbo].[trAfterUpdateInfoDoc]') IS NOT NULL
DROP TRIGGER [dbo].[trAfterUpdateInfoDoc]
GO
CREATE TRIGGER [dbo].[trAfterUpdateInfoDoc]
ON [dbo].[InfoDocs]
AFTER UPDATE
AS
BEGIN
--PLACE CODE HERE
END
GO