Selecting the second row of a table using rownum - sql

Question

I have tried the below query:
select empno from (
select empno
from emp
order by sal desc
)
where rownum = 2
This is not returning any records.
When I tried this query
select rownum,empno from (
select empno from emp order by sal desc)
It gives me this output:
ROWNUM EMPNO
1 7802
2 7809
3 7813
4 7823
Can anyone tell me what's the problem with my first query? Why is it not returning any records when I add the ROWNUM filter?

Answer 1

To explain this behaviour, we need to understand how Oracle processes
ROWNUM. When assigning ROWNUM to a row, Oracle starts at 1 and
only increments the value when a row is selected; that is, when all
conditions in the WHERE clause are met. Since our condition requires
that ROWNUM is greater than 2, no rows are selected and ROWNUM is
never incremented beyond 1.
The bottom line is that conditions such as the following will work as
expected.
.. WHERE rownum = 1;
.. WHERE rownum <= 10;
While queries with these conditions will always return zero rows.
.. WHERE rownum = 2;
.. WHERE rownum > 10;
Quoted from Understanding Oracle rownum
You should modify you query in this way in order to work:
select empno
from
(
select empno, rownum as rn
from (
select empno
from emp
order by sal desc
)
)
where rn=2;
EDIT: I've corrected the query to get the rownum after the order by sal desc

Answer 2

In the first query, the first row will have ROWNUM = 1 so will be rejected. The second row will also have ROWNUM = 1 (because the row before was rejected) and also be rejected, the third row will also have ROWNUM = 1 (because all rows before it were rejected) and also be rejected etc... The net result is that all rows are rejected.
The second query should not return the result you got. It should correctly assign ROWNUM after ORDER BY.
As a consequence of all this, you need to use not 2 but 3 levels of subqueries, like this:
SELECT EMPNO, SAL FROM ( -- Make sure row is not rejected before next ROWNUM can be assigned.
SELECT EMPNO, SAL, ROWNUM R FROM ( -- Make sure ROWNUM is assigned after ORDER BY.
SELECT EMPNO, SAL
FROM EMP
ORDER BY SAL DESC
)
)
WHERE R = 2
The result:
EMPNO SAL
---------------------- ----------------------
3 7813

Answer 3

try this:
SELECT ROW_NUMBER() OVER (ORDER BY empno) AS RowNum,
empno
FROM tableName
WHERE RowNumber = 2;
Snippet From Source:
SELECT last_name FROM
(SELECT last_name, ROW_NUMBER() OVER (ORDER BY last_name) R FROM employees)
WHERE R BETWEEN 51 and 100
REFERENCE

Answer 4

For nth row using rownum in oracle:
select * from TEST WHERE ROWNUM<=n
MINUS
select * from TEST WHERE ROWNUM<=(n-1);
Example for second row :
select * from TEST WHERE ROWNUM<=2
MINUS
select * from TEST WHERE ROWNUM<=1;

Answer 5

Select * From (SELECT *,
ROW_NUMBER() OVER(ORDER BY column_name DESC) AS mRow
FROM table_name
WHERE condition) as TT
Where TT.mRow=2;

Answer 6

Select Second Row From a Table in Oracle
SELECT *
FROM (SELECT * FROM emp ORDER BY rownum DESC)
WHERE rownum=1

Answer 7

try this way it's working 100%
SQL> SELECT * FROM STUD;
RNUMBER SNAME MARKS
104 mahesh 85
101 DHANU 20
102 BHARATH 10
100 RAJ 50
103 GOPI 65
SQL> select * from(select MARKS,ROWNUM AS RS from ( select * from stud order by marks desc)) where RS=2;
MARKS RS
65 2
SQL>

Answer 8

select empno
from
(
select empno,rownum as rum
from emp,
order by sal desc
)
where rum=2;

Answer 9

You can use RANK or DENSE_RANK to achieve what you are trying to achieve here.

Answer 10

Try this query 100% working
Select * from(select rownum as rn,emp.* from emp) Where rn=2;