Do I understand Apache+fastcgi+mysql interaction correctly?

Question

linux

Question for understanding. Let's say apache is running the prefork module. The php FastCGI mode is also selected. In doing so, we can configure both of these modules, for example like this:

<IfModule mpm_prefork_module>
MaxClients          64
</IfModule>

<IfModule mod_fcgid.c>
FcgidMaxProcesses 70
</IfModule>

I understand correctly that in this bundle FcgidMaxProcesses must always be greater than or equal to MaxClients. After all, in fact, apache will not create more than 64 processes, each of which can execute a maximum of 1 request to fastcgi, in total also 64?
If so, then why set FcgidMaxProcesses at all if there are no more of them than MaxClients anyway? And is it true that mysql's max-connections should also be greater than or equal to MaxClients ?
Or how?