mysql - How to order by user defined order/sort by number of items on a field

http://stackoverflow.com/questions/6345377/mysql-how-to-order-by-user-defined-order-sort-by-number-of-items-on-a-field

Using Django database layer outside of Django

http://stackoverflow.com/questions/2180415/using-django-database-layer-outside-of-django

How to redirect output to screen and a file

With the command tee (in Linux) or the command wtee (in Windows)

Example (in Linux)

ls | tee output.txt

Example (in Windows)

dir | wtee > output.txt

RMySQL - How to connect R with MySQL in Windows

Following the instructions of http://stackoverflow.com/questions/4785933/adding-rmysql-package-to-r-fails

Important note 1: The installation works when using MySQL for 32bit computers and R for 32bit computers. I have tried to install it to the 64bit version of R but I did not succeed.

• Install RTools
• Install MySQL or header and library files of mysql
• Create or edit file C:\Program Files\R\R-2.12.1\etc\Renviron.site and add two lines like CYGWIN=nodosfilewarning
MYSQL_HOME=C:/ARCHIV~1/MYSQL/MYSQLS~1.5
• Copy libmysql.lib from mysql/lib to mysql/lib/opt to meet dependencies.
• Copy libmysql.dll to C:\Program Files\R\R-2.12.1\bin or to windows/system32 directory.
• Run install.packages('RMySQL',type='source') and wait while compilation will end.

Important note 2: My computer contains Spanish language Windows, and I had several problems with the accent in the folder named "Configuración local", where the downloaded packages are stored and compiled.
I solved the problem in the following way. I changed the environment variable TMP to another local folder without containing any accent.
After the installation I rolled back the change in the environment variable.

MySQL - Get row number on select

http://stackoverflow.com/questions/2520357/mysql-get-row-number-on-select

SET @rank=0;
SELECT @rank:=@rank+1 AS rank, itemID, COUNT(*) as ordercount
  FROM orders
  GROUP BY itemID
  ORDER BY ordercount DESC;