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rownum [message #373209]

Wed, 04 April 2001 08:26

adelia
Messages: 45
Registered: April 2001

Member

What rownum does ?

select * from emp
where rownum < 10
order by hiredate desc
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Re: rownum [message #373212 is a reply to message #373209]

Wed, 04 April 2001 08:33

Prem
Messages: 79
Registered: August 1998

Member

adelia,

the above select will pick 10 records randomly and then order it by hiredate. i.e. it will perform the where condition first and then, on the result, perform the sorting.

hth

Prem :)

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Re: rownum [message #373214 is a reply to message #373209]

Wed, 04 April 2001 09:45

Krishnan
Messages: 18
Registered: October 2000

Junior Member

Rownum is performed prior to order by and hence you will only see those records that ordered and has their rownum <10. You may probably see no records or less than 10 records

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Re: rownum [message #373248 is a reply to message #373209]

Thu, 05 April 2001 23:38

Naresh
Messages: 27
Registered: March 2001

Junior Member

Hi Adelia,

The ROWNUM is a PSEUDOCOLUMN which returns a number indicating the order in which Oracle selects the row from a table. The first row selected has a ROWNUM of 1, the second has 2, and so on.

You can use ROWNUM to limit the number of rows returned by a query.

You can also use ROWNUM to assign unique values to each row of a table, as in this example:

UPDATE tabx
SET col1 = ROWNUM;

----------------------------

HTH

Naresh

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