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Question

This trigger updated every row in the table to with a new value after each insert

ALTER TRIGGER "tr_insert_eopi"
AFTER INSERT
ORDER 1
ON end_of_period_inventory
REFERENCING NEW as new_name
FOR EACH ROW
BEGIN

UPDATE end_of_period_inventory
SET reference_id = Cast( getDate() as char )
WHERE new_name.reference_id = '' or new_name.reference_id is null ;

END

Answer 1

You are mixing a row-level AFTER INSERT with a statement-level UPDATE, so the fact that multiple rows are updated should not come as a surprise (and the UPDATE might be called several times in case you would insert several times at once, say by a INSERT SELECT)...

If you want to alter the contents of a row during the insert, I'd highly recommend a BEFORE INSERT trigger. That would simply have a body with something like

if isnull(new_name.reference_id, '') = '' then
   set new_name.reference_id = cast( getDate() as char )
end if;

and all should be fine...

If you prefer to use an AFTER INSERT trigger, make sure to restrict the UPDATE statement to a single row by filtering on the primary key of the just inserted row.

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