[SQL] Create new sequence in a table

I need to create new sequence based on the SEQNO column below, I want the minimum SEQNO to always start with 1. How do I do that? I am not trying to alter the original table. I am just trying to add a new column to the data I pull so it is easier for me to join with other tables.

Below are the examples from the table. The column "Order" is the column I want to create when I pull the data based on column SEQNO.

ID SEQNO Order
N1 4 1
N1 7 2
N1 11 3
N2 3 1
N2 5 2


I didn't try anything because I don't know where to start.

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