Topic: DISTINCT or GROUP BY (Read 3507 times)

sphinx9999 · « **on:** February 14, 2008, 05:56:25 AM »

Which do you think is better, DISTINCT or GROUP BY?

SELECT DISTINCT id FROM phrase WHERE campaign LIKE 'proper%'

or

Code: [Select]

SELECT id FROM phrase WHERE campaign LIKE 'proper%' GROUP BY advert_id

I've asked this question before and received the following answer from a reliable source: "When there's just one column it doesn't matter". Do you agree?

Daniel0 · « **Reply #1 on:** February 14, 2008, 10:41:32 AM »

It depends on what you're trying to do.

aschk · « **Reply #2 on:** February 14, 2008, 10:47:36 AM »

GROUP BY

jaymc · « **Reply #3 on:** February 15, 2008, 10:46:54 AM »

Benchmark it ;-)

phpmyadmin is good, it tells you time taken to execute a query

freenity · « **Reply #4 on:** February 26, 2008, 12:52:08 PM »

I know old topic, but have a look at this: http://gwphp.feudal-times.net/?p=5
benchmarked and everything

Guess who wins

fenway · « **Reply #5 on:** February 27, 2008, 12:50:21 PM »

This is mainly because distinct is a filesort operation which group by has the chance to use an index or some temporary filesorting on smaller sets along the way.

goldfiles · « **Reply #6 on:** April 15, 2008, 11:36:18 PM »

Group By usually

abs0lut · « **Reply #7 on:** August 24, 2008, 06:54:09 AM »

i will not use distinct anymore

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Which is best to use when extracting one column, DISTINCT or GROUP BY?

Author Topic: DISTINCT or GROUP BY (Read 3507 times)

sphinx9999

DISTINCT or GROUP BY

Daniel0

Re: DISTINCT or GROUP BY

aschk

Re: DISTINCT or GROUP BY

jaymc

Re: DISTINCT or GROUP BY

freenity

Re: DISTINCT or GROUP BY

fenway

Re: DISTINCT or GROUP BY

goldfiles

Re: DISTINCT or GROUP BY

abs0lut

Re: DISTINCT or GROUP BY

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