Having the MySQL directories as set variables would make setting up a little quicker with less chance of human error since there will be one place/area to set all the options.

for German dateformat this would work

set year=%DATE:~6,4%
set day=%DATE:~0,2%
set mnt=%DATE:~3,2%
set hr=%TIME:~0,2%
set min=%TIME:~3,2%

IF %day% LSS 10 SET day=0%day:~1,1%
IF %mnt% LSS 10 SET mnt=0%mnt:~1,1%
IF %hr% LSS 10 SET hr=0%hr:~1,1%
IF %min% LSS 10 SET min=0%min:~1,1%

set backupdate=%year%-%day%-%mnt%-%hr%-%min%

---> FullBackup.2012-19-01-14-02

One thing I would like to point out though. When handling the zipped file further (eg. uploading it to ftp server) I have encountered problems with the file name. When the time was less then 10 it would leave a blank space in the file name and then it would not be possible to copy the file (using batch commands). It looked for example like this: FullBackup.2011-28-11- 9-34.zip -> the whole part after the space will be ignored when you use this file name for other operations. The same goes for days and month lower then 10.

The solution to this is simply parse the date and time string, check if it is less then 10 add zero to it in case it is.

set year=%DATE:~10,4%
set day=%DATE:~7,2%
set mnt=%DATE:~4,2%
set hr=%TIME:~0,2%
set min=%TIME:~3,2%

IF %day% LSS 10 SET day=0%day:~1,1%
IF %mnt% LSS 10 SET mnt=0%mnt:~1,1%
IF %hr% LSS 10 SET hr=0%hr:~1,1%
IF %min% LSS 10 SET min=0%min:~1,1%

set backupdate=%year%-%day%-%mnt%-%hr%-%min%

With this control sequence the file name would now be:
FullBackup.2011-28-11-09-34.zip -> no spaces = no problems

For those interested in uploading the backup file to some ftp server the commands are following:

cd\[path to directory where your file is saved]
@echo off
echo user [here comes your ftp username]>ftpup.dat
echo [here comes ftp password]>>ftpup.dat
echo [optional line; you can put "cd" command to navigate through the folders on the ftp server; eg. cd\folder1\folder2]>>ftpup.dat
echo binary>>ftpup.dat
echo put [file name comes here; eg. FullBackup.%backupdate%.zip]>>ftpup.dat
echo quit>>ftpup.dat
ftp -n -s:ftpup.dat [insert ftp server here; eg. myserver.com]
del ftpup.dat

Thanks again for this wonderful and beautifully simple solution. I hope my hints will be of help to others.
Matt feel free to include them in the article or the file itsefl.

Have a happy New year everyone.