It is impossible to use "what mysql" in zsh, but in bash it works

After upgrading to Ubuntu 12.04 LTS and installing mysql server 5.5, I can’t use “what mysql” in zsh, but it works in bash !! Here are my echoes:

    ZSH:
    $ whereis mysql
    mysql: /usr/bin/mysql /etc/mysql /usr/lib/mysql /usr/bin/X11/mysql /usr/share/mysql /usr/share/man/man1/mysql.1.g

    $ which mysql
    mysql: aliased to nocorrect mysql

    $ alias
    ...
    ...
    mysql='nocorrect mysql'
    ...
    ...

    BASH:
    $ whereis mysql
    mysql: /usr/bin/mysql /etc/mysql /usr/lib/mysql /usr/bin/X11/mysql /usr/share/mysql /usr/share/man/man1/mysql.1.g

    $ which mysql
    /usr/bin/mysql