Portinstall question

[Bill Schmitt (SW)]

I think I'm missing something basic, so if someone could point me to 
where that is, I would appreciate it. I been installing software using 
portinstall, but I think I'm missing something basic because there seems 
to be more guesswork involved that I expected there to be.

How do you know what name to use for the portinstall to work? For 
example, I wanted to install MySQL 41. The folders under 
/usr/ports/databases include several variations on my-sql. Among others 
are mysql323-server, mysql40-server, mysql41-server, and mysql50-server. 
In the Makefile for mysql41 it states PORTNAME?= mysql. But trying 
"portinstall mysql" or "portinstall mysql41" or "portinstall 
mysql41-server" all result in a message that the port doesn't exist. The 
command that works is "portinstall mysql-server", which I found with a 
basic google search, but I don't find that in the descriptions or 
Makefiles. Looking just at what is in the ports tree (or anywhere else 
on a 4.9 system), where would I properly find that name?