How to create a trigger to add if there is something to update???

Question

SQL

How the trigger works:
If we add the value "NameProduct" and "Kolichestvo" to the "Postavka" table, then in the "Sklad" table:
if not ,
then add the line "NameProduct" and "Kolichestvo"
if there is,
then update the line "NameProduct" and "Kolichestvo" .
How it is more correct to implement the trigger???

Answer 1

create or replace TRIGGER "DB"."TRG_TABLE"
AFTER INSERT OR UPDATE OR DELETE ON DB.TABLE
.........