T-SQL Row Number Restart after N

Question

How can I restart my Row_Number after a certain number of rows.

E.g.

How can I turn

ID  RowNumber
-------------
100 1
101 2
102 3
125 4
126 5         


        

Answer 1

Use the modulo operator:

select id, rownumber, 1 + ((rownumber - 1) % 4)
from table t;

If rownumber is not a column, you can also use the row_number() function:

select id, row_number() over (order by id),
       1 + ((row_number() over (order by id) - 1) % 4)
from table t;