sql - Counting the number of dowloads on a database oracle -

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i creating database online store going sell, movies, music , books final project in uni.

i have created tables , made sure working. database supposed have "historical" table. want have on thistab number of downloads specific client makes.

the primary keys on table "clients" suscriber_number , id_download. these 2 foreign keys-primary key on historical tab. how can make sure thatevery download client makes gets store on historical tab new download , not replacement of previous data? afraid override previous information , not keep count of downloads on each suscriber. able keep track in oracle of times using update statement on existing data retrieve later on?


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