thank you gomer and mfillpot ,it was a very good answer all my doubts were killed !!!
good luck!!!

:( i need to do an exercise(mount and unmount a pen-disk,floppy and a CD-ROM ) , but Linux does not have a c:\ drive or F:\drive but i'm getting confused with the command line results,i'm using ubuntu 10.04 distribution so all the divices plugged in are at /media so i write $umount /media/antonio (antonio is my pen-drive) then i write ls /media and there is any antonio dir or something but i can still see it in places window, did i do it right? even i can see it if i write fdisk -l . is that mounting an unmounting

another point , how do i identify partitions and internal devices to mount and umount them?.All i know is they are inside /dev

i hope you could helpme =)
have a nice day :laugh:

oh thank you for the fastest reply, i found some graphics at MySQL webpage but the results seems to be suspicious now i can compare results....

note if you are interested in this study check this URL http://www.mysql.com/why-mysql/marketshare/

have a nice day!!!

i'm a student of IT , so i want to know if there is a statistical study which determines the most used DBMS.Sorry if i'm posting at the wrong place but i did not know where to post this.I would appreciate your help , have a nice day =) .