Exercise 7.3. ROW_NUMBER, RANK and DENSE_RANK side by side at Rungkut.   [12 row(s)]
Service_id | bills | row_no | rnk | dense
-----------+-------+--------+-----+------
S0001      | 596   | 1      | 1   | 1
S0002      | 155   | 2      | 2   | 2
S0003      | 132   | 3      | 3   | 3
S0008      | 78    | 4      | 4   | 4
S0004      | 72    | 5      | 5   | 5
S0009      | 54    | 6      | 6   | 6
S0011      | 43    | 7      | 7   | 7
S0006      | 41    | 9      | 8   | 8
S0007      | 41    | 8      | 8   | 8
S0012      | 37    | 10     | 10  | 9
S0005      | 36    | 11     | 11  | 10
S0010      | 27    | 12     | 12  | 11

