As we can see in the solution:

Expression are evaluated in the column order in the select clause.

This is the same for the where clause.  An advice is to test first the expression that get more chance to return false at the head of the where conditions :   

1. SET @BRAND=0;
2. SET @ct=0;
3. SELECT
4.  *
5. FROM
6.  (SELECT
7.    IF(@BRAND<>id_BRAND,@ct:=0 ,@ct:=@ct ) ,
8.    @ct:=@ct+1 AS ct,   
9.    @BRAND:=id_BRAND,
10.    t2.*
11.   FROM
12.    (SELECT
13.      st.ID_BRAND,
14.      st.ID_MODEL,
15.      SUM(COMPTE) AS total,
16.      AVG(totalm)
17.   …

Read the original article at The Mythical MySQL DBA

I’ve  been getting more than my fair share of calls from recruiters of late. Even in this depressed economic climate where jobs are rarer than a cab at rush-hour, it’s heartening to know that tech engineers are in great demand. And it’s even more heartening to think that demand for MySQL DBAs has never been better.

My reckoning was confirmed by a Bloomberg news report about stalwart retailers suffering from a dearth of talented engineers. Bloomberg cited Target’s outage-prone e-commerce site as a symptom of, among other things the market’s shortage. One of the challenges old-timers like Target face is having to compete with Silicon Valley startups as a …

The reason we are confident that the comparative decline in the use of the GNU GPL family of licenses and the increasing significance of complementary vendors in relation to funding for open source software-related vendors will continue is due to the analysis of our database of more than 400 open source software-related vendors, past and present.

We previously used the database to analyze the engagement of vendors with open source projects for our Control and Community report, plotting the strategies used by the vendors against the year in which they first began to engage with open source projects …

Thanks to the extraordinary work of volunteer superstar Richard Laskey, the videos for the September, October and November Boston MySQL user group meetings are available. Whether you want to encrypt, renormalize or learn how MTV uses MongoDB, there are now full-length videos available:

MongoDB @MTV by Jeff Yemin of MTV Networks, September 2011

Renormalize - Solving Performance Problems in MySQL without Denormalization by Ari Weil of Akiban, October 2011.

MySQL Encryption with Gazzang by Mike Frank of Gazzang, November 2011.

Enjoy the videos! …

MySQL::Sandbox 3.0.24 was released yesterday, with many new features. More than vanilla MySQLIf you have missed my previous announcement, here's the gist of it. MySQL Sandbox can now deal with tarballs from either Percona Server or MariaDB. The main difference after this change is that you can now create a directory called <PREFIX>5.5.16 and make_sandbox will recognize it as well as the plain 5.5.16.

$ make_sandbox --export_binaries --add_prefix=ps \
   Percona-Server-5.5.11-rel20.2-114.Darwin.i386.tar.gz  \
   -- --sandbox_directory=msb_ps5_5_11
unpacking Percona-Server-5.5.11-rel20.2-114.Darwin.i386.tar.gz
[…]
installing with the following …

The MySQL Runtime team is look for Windows Server developers. Windows is a very important platform for MySQL and we need good folks to help drive the product forward. Pass the word (and the URL) to those with these qualities.

…

In previous posts I described how row conflicts are detected using epochs. In this post I describe how they are handled.

Row based conflict handling with NDB$EPOCH

Once a row conflict is detected, as well as rejecting the row change, row based conflict handling in the Slave will :

• Increment conflict counters
• Optionally insert a row into an exceptions table
  

For NDB$EPOCH, conflict detection and handling operates on one Cluster in an Active-Active pair designated as the Primary. When a Slave MySQLD attached to the Primary Cluster detects a conflict between data stored in the Primary and a replicated event …

MySQL is developing rapidly.  And today it does not only happen along a single track but in multiple directions simultaneously.

This is due to both server ‘forks‘ as well as various plugins and 3rd party storage engines available.   Each of those will often add  information that can be fetched from the server – typically in the form of additional Information_Schema tables. This content can now also be utilized for monitoring MySQL servers with MONyog. MONyog 4.8  implements monitoring based on Custom SQL Objects.  It is basically just a SQL query. Any query returning a result set can be used for monitoring.  MONyog will collect results from the query and you may define counters on it exactly as you want.

It is really very simple.  In this example we will …

Here are some of the fake O'Reilly book covers I mentioned in a prior post.  These have been optimized for use as black & white Kindle screensaver wallpaper images.  If you haven't done so already, you can install a Kindle screensaver hack with a couple of downloads. 

Update: I've embedded a slideshow from PicasaWeb, but it requires Flash.  If you don't see it you can click on the links below to go directly to PicasaWeb.

• Kindle hacks:  …

We wish all our customers, users and partners a Merry Xmas and a Happy New Year.

The year of 2011 has been a terrific year for us.  But first let us have a look at where we started 10 years ago. The first version of SQLyog was released in the spring of 2002 – what will mark our 10 year anniversary as a company early next year. In the period since then we have seen quite a lot of other MySQL clients come and go. We are happy to see most of our existing customers upgrade regularly, to see our user base increase, and we are happy to do our best to provide the solutions requested by users and to keep pace with MySQL development.

And also 4½ years ago we added MONyog to our portfolio. So there will be another important anniversary to celebrate in 2012 as well. MONyog has also proved to be robust and long-lived.

We are …