Help with Trigger

On 12/28/2016 07:06 PM, Clifford Snow wrote:

I'm trying to write a trigger (my first) to update another table if the
user_id is new. But I'm getting a index exception that the user_id

What is the actual error message?

already exists. I'm picking up data from another feed which gives
provides me with changes to the main database.

what I have is

CREATE OR REPLACE FUNCTION add_new_user()
RETURNS TRIGGER AS
$BODY$
DECLARE
commits RECORD;
BEGIN
SELECT INTO commits * FROM changes WHERE user_id = NEW.user_id;

In the above you are checking whether the changes table has the user_id
and if does not then creating a new user in the user table below. Not
sure how they are related, but from the description of the error it
would seem they are not that tightly coupled. In other words just
because the user_id does not exist in changes does not ensure it also
absent from the table user. Off the top of head I would say the below
might be a better query:

SELECT INTO commits * FROM user WHERE user_id = NEW.user_id;

Though it would help the debugging process if you showed the complete
schema for both the changes and user tables.

IF NOT FOUND
THEN
INSERT INTO user (user_name, user_id, change_id,
created_date)
VALUES(NEW.user_name, NEW.user_id,
NEW.change_id, NEW.created_date);
END IF;
RETURN NEW;
END;
$BODY$
LANGUAGE plpgsql;

CREATE TRIGGER add_new_user_trigger
BEFORE INSERT ON changes
FOR EACH ROW
EXECUTE PROCEDURE add_new_user();

I hoping for some recommendations on how to fix or at where I'm going wrong.

Thanks,
Clifford

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--
Adrian Klaver
adrian.klaver@aklaver.com

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Thank you for your suggestion which solved the problem. Much better
solution that what I was trying to accomplish. Much smaller table to query
since it only has one entry per user.

Clifford

On Wed, Dec 28, 2016 at 8:12 PM, Adrian Klaver <adrian.klaver@aklaver.com>
wrote:

On 12/28/2016 07:06 PM, Clifford Snow wrote:

I'm trying to write a trigger (my first) to update another table if the
user_id is new. But I'm getting a index exception that the user_id

What is the actual error message?

already exists. I'm picking up data from another feed which gives

provides me with changes to the main database.

what I have is

CREATE OR REPLACE FUNCTION add_new_user()
RETURNS TRIGGER AS
$BODY$
DECLARE
commits RECORD;
BEGIN
SELECT INTO commits * FROM changes WHERE user_id = NEW.user_id;

In the above you are checking whether the changes table has the user_id
and if does not then creating a new user in the user table below. Not sure
how they are related, but from the description of the error it would seem
they are not that tightly coupled. In other words just because the user_id
does not exist in changes does not ensure it also absent from the table
user. Off the top of head I would say the below might be a better query:

SELECT INTO commits * FROM user WHERE user_id = NEW.user_id;

Though it would help the debugging process if you showed the complete
schema for both the changes and user tables.

IF NOT FOUND

THEN
INSERT INTO user (user_name, user_id, change_id,
created_date)
VALUES(NEW.user_name, NEW.user_id,
NEW.change_id, NEW.created_date);
END IF;
RETURN NEW;
END;
$BODY$
LANGUAGE plpgsql;

CREATE TRIGGER add_new_user_trigger
BEFORE INSERT ON changes
FOR EACH ROW
EXECUTE PROCEDURE add_new_user();

I hoping for some recommendations on how to fix or at where I'm going
wrong.

Thanks,
Clifford

--
@osm_seattle
osm_seattle.snowandsnow.us <http://osm_seattle.snowandsnow.us&gt;
OpenStreetMap: Maps with a human touch

--
Adrian Klaver
adrian.klaver@aklaver.com

--
@osm_seattle
osm_seattle.snowandsnow.us
OpenStreetMap: Maps with a human touch