Trigger syntax

Question

Hi,
I following some tutorials on SQL triggers but I have a question regarding the syntax, which none of the tutorials i looked at explains:
The aim of my trigger is when the table dbo.RBD_Measure is updated then the trigger fires and (after the update) inserts the Primary Key values from PK column in dbo.RBD_Dimension table into the FK column in dbo.RBD_Measure where RBD columns contain
same values in both table.
I have the code below and it works fine but what i would like to know is what exactly is the difference between having the SQL statements after AS (as in the example below), or having it between BEGIN...END part of the code. Can someone explain what should
come after AS (or what not) and what should come between BEGIN...END?
CREATE TRIGGER [dbo].[Trigger_Update]
ON [dbo].[RBD_Measure]
for insert
AS
update RBD_Measure
Set RBD_Measure.FK=RBD_Dimension.PK
FROM RBD_Measure
INNER JOIN RBD_Dimension
on Rbd_Measure.RBD=RBD_Dimension.RBD
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON;
-- Insert statements for trigger here
END
Thanks!

Answer 1

The aim of my trigger is when the table dbo.RBD_Measure is updated then the trigger fires and (after the update) inserts the Primary Key values from PK column in dbo.RBD_Dimension table into the FK column in dbo.RBD_Measure where RBD columns contain
same values in both table.
I have the code below and it works fine but what i would like to know is what exactly is the difference between having the SQL statements after AS (as in the example below), or having it between BEGIN...END part of the code. Can someone explain what should
come after AS (or what not) and what should come between BEGIN...END?
Although it is common practice to specify BEGIN/END to encapsulate the entire code block in triggers (and other modules), it is optional.
Be aware that because you are not joining to the inserted table in your trigger, every row in the RBD_Measure is updated every time this trigger executes regardless of whether the row was inserted by the statement that fired the trigger.  You mention
"after update" but this trigger fires only after INSERT statements.  You can fire the trigger after both inserts and updates, and also join to the inserted table to identify the updated and inserted rows.  Below is an example that assumes the RDB_Measure
table has a primary key column named RBD_Message_PK:
CREATE TRIGGER [dbo].[Trigger_Update_Insert]
ON [dbo].[RBD_Measure]
FOR UPDATE, INSERT
AS
UPDATE m
SET FK = RBD_Dimension.PK
FROM RBD_Measure AS m
INNER JOIN RBD_Dimension AS d
ON m.RBD = d.RBD
INNER JOIN inserted AS i ON
i.RBD_Measure_PK = m.RBD_Measure_PK;
GO
Dan Guzman, SQL Server MVP, http://www.dbdelta.com