Assign ID to every group of result

Question

Hi all,
I have this problem to assign serial ID to every group of result for my SQL. Let say if I want to group date for 11 data and my result returned 5 groups of date. Is there any way I can create a SQL statement that can assign ID for each group of date without using 'GROUP BY'? Using example count() over total maybe?

Answer 1

Use DENSE_RANK analytic function
with c as
select sysdate DT,1 ID,'VAL1'  VAL FROM DUAL UNION ALL
select sysdate DT,2 ID,'VAL2'  VAL FROM DUAL UNION ALL
select sysdate DT,3 ID,'VAL3'  VAL FROM DUAL UNION ALL
select sysdate-2 DT,4 ID,'VAL4'  VAL FROM DUAL UNION ALL
select sysdate-2 DT,5 ID,'VAL5'  VAL FROM DUAL UNION ALL
select sysdate-4 DT,6 ID,'VAL7'  VAL FROM DUAL UNION ALL
select sysdate-4 DT,7 ID,'VAL6'  VAL FROM DUAL UNION ALL
select sysdate-4 DT,8 ID,'VAL8'  VAL FROM DUAL UNION ALL
select sysdate-5 DT,9 ID,'VAL9'  VAL FROM DUAL )
SELECT DENSE_RANK() OVER (ORDER BY TRUNC(DT) DESC ) RN, DT,ID,VAL
FROM C
        RN DT                ID VAL
         1 13-AUG-10          1 VAL1
         1 13-AUG-10          2 VAL2
         1 13-AUG-10          3 VAL3
         2 11-AUG-10          4 VAL4
         2 11-AUG-10          5 VAL5
         3 09-AUG-10          6 VAL7
         3 09-AUG-10          7 VAL6
         3 09-AUG-10          8 VAL8
         4 08-AUG-10          9 VAL9
9 rows selected.