Question

IF EXISTS (SELECT name FROM sysobjects WHERE name = 'myTrigger' AND type = 'TR')
BEGIN
    DROP TRIGGER myTrigger
END
GO
go
create trigger myTrigger
on mytable_backup
instead of insert
as
begin
  declare @seq int
  select @seq = seq from inserted 
  if exists (select * from mytable_backup where seq= @seq) begin
      delete from mytable_backup where seq=@seq
  end
  insert into mytable_backup
  select * from inserted
end
go

I’ve written this trigger to check while inserting if seq column is repeated then update the previous row with same seq if seq doesn’t exits insert it with new seq.

In ssis package I’m using OLEDB table(Mytable) as a source which contains.

Name,Age,Seq
Gauraw,30,1
Gauraw,31,1
Kiran,28,3
Kiran,29,3
kiran,28,3
Venkatesh,,4
Venkatesh,28,4

Now I’m loading this table to OLEDB destination(Mytable_backup) as destination.
I suppose to get output as.

Gauraw,31,1
kiran,28,3
Venkatesh,28,4

But I’m getting all the records from Mytable into Mytable_backup.

is anything wrong with my trigger?

Answer 1

I think that this trigger will just take the first row and compare it with the existing. If I understand what you want to do you can quit easy do this:

IF EXISTS (SELECT name FROM sysobjects WHERE name = 'myTrigger' AND type = 'TR')
BEGIN
    DROP TRIGGER myTrigger
END
GO
go
create trigger myTrigger
on mytable_backup
instead of insert
as
begin
insert into mytable_backup
select 
    * 
from 
    inserted
WHERE NOT EXISTS
    (
        SELECT
            NULL
        FROM
            mytable_backup AS mytable
        WHERE
            inserted.seq=mytable.seq
    )
end
go

EDIT

So I found out what was going on. If you insert all of the rows in one go the inserted contains all the rows.. Sorry my mistake. If there are duplicates in your data your example do not show which to choose. I have chosen the one with the maximum of age (don’t know what your requirements is). Here is a update with the full example

Table structure

CREATE TABLE mytable_backup
(
    Name VARCHAR(100),
    Age INT,
    Seq INT
)
GO

Trigger

create trigger myTrigger
on mytable_backup
instead of insert
as
begin
;WITH CTE
AS
(
    SELECT
        ROW_NUMBER() OVER(PARTITION BY inserted.Seq ORDER BY Age) AS RowNbr,
        inserted.*
    FROM
        inserted
    WHERE NOT EXISTS
    (
        SELECT
            NULL
        FROM
            mytable_backup
        WHERE
            mytable_backup.Seq=inserted.Seq
    )
)
insert into mytable_backup(Age,Name,Seq)
SELECT
    CTE.Age,
    CTE.Name,
    cte.Seq
FROM
    CTE
WHERE
    CTE.RowNbr=1
end
GO

Insert of test data

INSERT INTO mytable_backup
VALUES
    ('Gauraw',30,1),
    ('Gauraw',31,1),
    ('Kiran',28,3),
    ('Kiran',29,3),
    ('kiran',28,3),
    ('Venkatesh',20,4),
    ('Venkatesh',28,4)

SELECT * FROM mytable_backup

Drop of the database objects

DROP TRIGGER myTrigger
DROP TABLE mytable_backup