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every 5th row data extraction [message #19933]

Thu, 18 April 2002 23:33

Jay
Messages: 127
Registered: October 1999

Senior Member

If i want to extract every fifth row of from the table what will be the qrery kind of ..? please take an example of emp table here.

thank you
Jay

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Re: every 5th row data extraction [message #19935 is a reply to message #19933]

Fri, 19 April 2002 00:29

Mike
Messages: 417
Registered: September 1998

Senior Member

Hi,

It's up to you to define what the 5th row is. There is no information stored in a table about row number or which row is the 5th row.

Mike

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Re: every 5th row data extraction [message #19948 is a reply to message #19933]

Fri, 19 April 2002 15:18

Todd Barry
Messages: 4819
Registered: August 2001

Senior Member

You can use DBMS_RANDOM if you truly want a random selection. If you would rather base the selection on a particular column, you can instead order by that column (example: employee number).

select *
  from (select rownum rn, t.*
          from emp t
         order by dbms_random.random) 
 where mod(rn, 5) = 0

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