Query to get a group having n rows each

Question

I have emp table empl_id in sorted order and i need column value "Group no"  based on value of N. (making a group start with 1 having n employees each)
N=2
emp_id    Name   Group No
1001          A            1
1003         B             1
1004         C             2
1006         D             2
1007         E             3
1009         F             3
N=3
emp_id    Name   Group No
1001          A            1
1003         B             1
1004         C             1
1006         D             2
1007         E             2
1009         F             2
Your SQL is highly appricated.

Answer 1

Hi,
Since I don't have a sample version of your table, I'll use scott.emp.
Here's one way:
VARIABLE  n   NUMBER
EXEC     :n := 3;
SELECT    empno, ename
,         CEIL ( ROW_NUMBER () OVER (ORDER BY ename)
               / :n
               )       AS group_no
FROM      scott.emp
ORDER BY  ename
The highest-numbered group may have fewer members than the others.  For example, scott.emp has 14 rows.  There's no way to assign every row to a single group and have 3 members in each group; there is no integer X such that 3 * X = 14.  So the query above assigns 3 members to group_nos 1 through 4, but only assigns 2 rows to group_no=5.