Help needed in generating the query

Question

Hi All,
While fetching the required columns from the table, i also have to display the seq no starting with some no. ( which will vary based on the functionality, so it ll be a sep variable.) and will get incremented with a offset value.
Current code:
select col1, col2, col3 from table1 where col1 = valid_condition; Expected code / Or approach:
select start_val+offset_val , col1, col2, col3 from table1 where col1 = valid_condition; This select query is part of a view and the values for start_val, offset_val will be set as global params.
Is there any easier way of implementing this in the query, other than creating a seq no.
thanks in advance.

Answer 1

Hi,
This sounds like a job for ROWNUM or ROW_NUMBER.
The ROWNUM pseudo-column is easy to use, but the numbers aren't necessarily assigned in the order you'd like:
SELECT       ename
,       1000 + ROWNUM          AS seq_no
FROM       scott.emp
WHERE       deptno     = 30
ORDER BY  ename
;Output:
ENAME          SEQ_NO
ALLEN            1001
BLAKE            1004
JAMES            1006
MARTIN           1003
TURNER           1005
WARD             1002To assign the numbers in order, you could select ROWNUM from an ordered sub-query (or view), but if you're going to that much trouble, you might as well use the analytic ROW_NUMBER function:
SELECT       ename
,       1000 + ROW_NUMBER () OVER (ORDER BY ename)          AS seq_no
FROM       scott.emp
WHERE       deptno     = 30
ORDER BY  ename
;Output:
ENAME          SEQ_NO
ALLEN            1001
BLAKE            1002
JAMES            1003
MARTIN           1004
TURNER           1005
WARD             1006Edited by: Frank Kulash on Nov 25, 2009 1:32 PM