Welcome to the community, @Mohsen_khaldoun! It’s best not to duplicate info across multiple tables. One of the elements of good database design is that each type of data will have one place where it can be found. In your case, all student data will live on the
[Students] table. If you’re in the
[Marks] table and want to refer to a specific student—for example, to record the student’s marks for an assignment—you would add a link field where you can create a link to the student record in the
[Students] table. Using that link, you could pull in other info from that student’s record using a lookup field, but that original student record is still the master place to record and edit all of that student’s details. When that student’s record changes, any records in other tables that link to that student record will see those changes via any lookup fields you might have made.
Does that make sense?