The new created terminal can not find the file use which in Mac
If you modify the PATH variable in a Terminal session by exporting it (e.g. export PATH="/usr/local/mysql/bin:$PATH" it will be expired in the next session.

So either edit the file ~/.bash_profile or edit /private/etc/paths if you need this PATH for other users also.

In ~/.bash_profile add the line:

export PATH="/usr/local/mysql/bin:$PATH"


In /private/etc/paths add the line

/usr/local/mysql/bin


Close your current Terminal session, launch a new one to enable the new PATH and check the result:

echo $PATH
which mysql_config