SQL Server : Triggers for Insert - sql-server

Question

create table tab(id int identity,task_id int,task_descp varchar(10),task_code varchar(10))
insert into tab values(7,'BUS','B')
insert into tab values(3,'CAR','C')
create table tab_detail( task_descp varchar(10),task_code varchar(10),color varchar(10))
create trigger tab_trigger on tab for insert as
declare #task_descp varchar(10)
declare #task_code varchar(10)
declare #task_id int
set #task_descp=i.task_descp from inserted i
set #task_code=i.task_code from inserted i
set #task_id=i.task_id from inserted i
if(#task_id=7)
insert into tab_detail values(#task_descp,#task_code,'BLUE')
if(#task_id=3)
insert into tab_detail values(#task_descp,#task_code,'GREEN')
go
I want to create a trigger for table tab where if I insert a record based on the task_id column a record has to be inserted into another table tab_detail.
When executing this I get this error:
Incorrect syntax near the keyword 'from'

Answer 1

Instead of:
set #task_descp=i.task_descp from inserted i
Try this:
select #task_descp=i.task_descp from inserted i
Or you could do this:
create trigger tab_trigger on tab for insert as
insert into tab_detail
select task_descp, task_code, case #task_id when 7 then 'BLUE' else 'GREEN' end
from inserted
where taskid in (7,3)
go

Answer 2

Change the SET to SELECT. Also, inserted is a recordset, not a single value. Fixing the code issue still might result in a run time issue!
This code should work fine for a recordset of information.
CREATE TRIGGER tab_trigger ON tab FOR INSERT AS
BEGIN
-- nothing to do?
IF (##rowcount = 0) RETURN;
-- do not count rows
SET NOCOUNT ON;
-- inserted data
INSERT INTO tab_detail
SELECT
i.task_descp,
i.task_code,
CASE i.taskcode
WHEN 7 THEN 'BLUE'
WHEN 3 THEN 'GREEN'
ELSE ''
END
FROM inserted i
WHERE i.task_code in (3, 7)
END
GO