How to get previous record before the last one?

HI

I have a table like this named Profiles:

!dMain, IdProfile, Qty
1                17        20
2                17        33
3                18        25
4                18        30
5                17        10
6                17         5

I want to get the previuous record regarding the last added one per each IdProfile using SQL, something like this:

!dMain, IdProfile, Qty
3                18        25
5                17        10

Thanks in advance.
dimensionavAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Kevin CrossChief Technology OfficerCommented:
The idMain values are not necessarily sequential, correct?  In other words, can the previous row may be several ids back?
Kevin CrossChief Technology OfficerCommented:
Here is one way to accomplish this.  It works whether or not the previous idMain is close or not.

SELECT idMain, idProfile, Qty
FROM (

SELECT idMain, Qty
     , /* if profile is same as row above,
          increment row number; else, start at 1. */
       if(idProfile = @lastprofile,
          @rownum:=@rownum+1,
          @rownum:=1) as ranking
     , /* since we are using @lastprofile in @rownum,
          we have to set @lastprofile 2nd;
          otherwise, the current and last always would equal.
        */
       @lastprofile:=idProfile as idProfile
FROM eePrvTest, 
(SELECT @rownum:=0, @lastprofile:=null) r
ORDER BY idProfile, idMain DESC

) derived
WHERE ranking = 2
;

Open in new window


The ranking approach is from an article I wrote, so you can read for further explanation:
http://www.experts-exchange.com/Microsoft/Development/MS_Access/A_1555-Analytical-SQL-Where-do-you-rank.html

The key is the solution ranks the records in reverse idMain order; therefore, the outer SELECT gets the second ranked row with the first being the last entry.

I hope that makes sense.

Best regards and happy coding,

Kevin

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
dimensionavAuthor Commented:
The idMain values are not necessarily sequential, correct?  In other words, can the previous row may be several ids back?
 YES, can be several ids back.

Kevin, just a question, does your solution works for MySQL?
Thanks for everything.
Kevin CrossChief Technology OfficerCommented:
The solution I gave is specific to MySQL.  It would be different syntax for other languages.  The article I wrote explains the different implementations across different SQL platforms in case you need to create something similar in other systems.
snoyes_jwCommented:
Here's another way, that does not require variables or subqueries.
SELECT p1.* 
FROM profiles p1 
JOIN profiles p2 ON p1.idMain < p2.idMain AND p1.idProfile = p2.idProfile 
GROUP BY p1.idMain 
HAVING COUNT(*) = 1;

Open in new window

It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Query Syntax

From novice to tech pro — start learning today.