Difference between rowid and rownum


Difference between rowid and rownum

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Oracle - Difference between rowid and rownum - Feb 18, 2010 at 11:00 PM by Rajmeet Ghai

Explain the difference between rowid and rownum.  

ROWID is a unique pseudo number assigned to a row. Rownum returns the number of rows for a resultant query. BOTH are pseudo columns not occupying any physical space in the database.

Example of Rownum:
Sort salary and return first 5 rows.
select * from
( select *
       from emp 
       order by sal desc )
where ROWNUM <= 5;

Example of Rowid:
Below query selects address of all rows that contain data for students in department 20
SELECT ROWID, last_name
       FROM student
       WHERE department_id = 20;

Oracle - Difference between rowid and rownum - April 10, 2009 at 11:00 AM

Explain the difference between rowid and rownum.  

RowId represents a row in a table internally. It can be used for fast access to the row. Rownum is a function of the result set.
select * from Student where rownum = 2 will get the first 2 rows of your result set.

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Discussion Board

Shuvam is correct

King 05-6-2013 03:39 PM



You have wrong concept of ROWNUM.

King 05-6-2013 03:38 PM

Rownum reference

As shown above to select first two rowsthe code written is...
select * from where rownum=2.
I do have a doubt if we really we can write a "rownum =2".Equality operator can only be assigned if we write rownum=1..otherwise except 1 it does not go with any of the number assigned with rownum...
Rather to select first two rows of a table the query can be written like this.
Thanks and regards,

shuvam dutta 10-15-2012 01:44 AM




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