Did my trigger fire from and update, insert, or delete?

I recently got a question on a trigger and I could see that the coder was trying to handle two operations in a single trigger and perform separate actions based on the operation.

Now, we all know that we could create a separate trigger for each operation.  However, it is sometimes helpful for maintaining code if we use a single trigger.


Here is a simple example of how to handle the different operations in a single trigger.

create table test(
myfield varchar(1)
)
go

create  TRIGGER cstr_test
ON test
AFTER INSERT, UPDATE, DELETE
AS
BEGIN
if exists(select 1 from deleted)
begin
if exists(select 1 from inserted)
begin
print 'update'
end
else
begin
print 'delete'
end
end
else
begin
print 'insert'

end
END
go


insert into test select 1

update test set myfield=2 where myfield=1

delete from test



I hope this helps someone!