I need to identify which products a subscriber has in data file field so I don't show him/her the same products in the email. e.g. the column header called "Products" has this value: product 1 || product 2 || product 4 || product 7. In this case this subscriber will receive 3, 6 and 8.
They use || in between products as per my example.
How can I identify what products are there through AMPscript?