OraFAQ Forum: SQL & PL/SQL » Using Distinct to sort

Home » SQL & PL/SQL » SQL & PL/SQL » Using Distinct to sort

Show: Today's Messages :: Polls :: Message Navigator
E-mail to friend

Using Distinct to sort [message #1115]

Tue, 02 April 2002 15:21

Lisa
Messages: 31
Registered: September 2000

Member

Does "distinct" perform a sort? And if so, is it by ascending order? Therefore, if I am using "distinct", I do not need to include "order by".
Example:
Select DISTINCT user from user_table;

Report message to a moderator

Re: Using Distinct to sort [message #1118 is a reply to message #1115]

Tue, 02 April 2002 18:03

fidelia
Messages: 3
Registered: April 2002

Junior Member

Distinct does not automatically sort the column, therefore you still need to use order by clause.

Report message to a moderator

Re: Using Distinct to sort [message #1131 is a reply to message #1118]

Wed, 03 April 2002 08:29

Lisa
Messages: 31
Registered: September 2000

Member

I've been researching and I believe that it does use a sort.

Optimizing Sorts

The following operations require Oracle to perform a sort: Creating an Index, ORDER BY, GROUP BY, DISTINCT, UNION, INTERSECT and MINUS.

Source:
http://www.oraclenotes.com/study_brief/ocp8_SB_performance_tuning.htm

Report message to a moderator

Re: Using Distinct to sort [message #1134 is a reply to message #1115]

Wed, 03 April 2002 09:44

Todd Barry
Messages: 4819
Registered: August 2001

Senior Member

You always need to include an ORDER BY clause to ensure that your result set is in a particular order.

Although at times it seems you can rely on GROUP BY or DISTINCT to do the "ordering" for you, this is not always the case.

Report message to a moderator

Previous Topic:	Primary Key Information
Next Topic:	Dynamic SQL and Cursor

Goto Forum:

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

]

Current Time: Thu Apr 25 21:17:39 CDT 2024