why I cannot cd into /var/lib/mysql

Question

The structure is the following

ravas@ravas-desk-lmde /var/lib $ pwd
/var/lib
ravas@ravas-desk-lmde /var/lib $ ls -l | grep mysql
drwx------ 13 mysql   mysql   4096 Feb 10 22:32 mysql

When I try to get into /var/lib/mysql, I don't have rights

ravas@ravas-desk-lmde /var/lib $ cd mysql/
bash: cd: mysql/: Permission denied

though I belong to the mysql group

ravas@ravas-desk-lmde /var/lib $ groups ravas 
ravas : ravas adm dialout cdrom floppy sudo audio dip video plugdev lpadmin sambashare mysql

What's the problem here?

Answer 1

sudo -i

then

cd /var/lib/mysql/

Answer 2

mysql user is the only one that can access to the directory, you can use root to access there and change permissions, or you can change the directory permissions to 740 with

chmod 740 /var/lib/mysql

permissions are divided in 3 parts user/group/else. and you have

drwx------

d= directory

r= read = 4

w=write = 2

x=execute = 1

so the "owner" has read(4) + write(2) + execute(1) = 7 permissions in that directory

every one else doesn't