Restoring numbering in the database, the field is not auto-increment?

Question

MySQL

There is a table. 8 entries are entered into the table with each addition (1 pack = 8 entries). These eight records have a field responsible for the position, respectively, it is the same for each pack.
For the first eight it will be 1, for the second eight it will be 2, and so on. (I would kill for such an organization). After the pack is removed, the sequence is broken.
For example, if you deleted the second pack, then there are 8 records left with the value 1 and 8 with the value 3.
The question is: how to return the sequence to each pack after each deletion?
MySQL, I didn't write it, they asked me to fix it. I'm shocked.

Answer 1

Maybe so?
UPDATE table SET index = index - 1 WHERE index > 2

Answer 2

Eh ... well then:

Select @i:=0; Update TBL Set index = @i := @i +1, index = floor(index/8);

Answer 3

And why, in fact, hole-free is required?

Answer 4

What does "return sequence" mean? If pack 2 is deleted, then all packs from number 3 to the last should be updated, right? And if not a complete pack is removed, can it be? What if it's added?