Raul Said:

What are good languages to write complicated web based software in?

We Answered:

PHP is a very powerfull language, you can create some very complex websites with it. Its also open source, and free to use. This is one advantage it has over other languages such as ASP,

ASP is similar, but its Microsofts verison, im sure it has features PHP hasnt got, and PHPhas some this hasnt got, but ASP only runs on microsoft serversas far as i am aware, alsi it comes with .NET librarys to allow the develeper to make more complex websites / apps

Then you have JSP (Java Server Pages) which uses Java,
Also, Perl, Python, Ruby, etc.. there are more...

http://www.php.net/
http://www.asp.net/
http://www.ruby-lang.org/en/
http://www.python.org/

These are all serverside scripting languages, do a search on google for them and see which one you like best

All of these connect to databases such as MySQL, Ms SQL, Oracle etc...

There isnt really a best language to learn, my preference would be PHP, because it has similar syntax to C#, if you find an online CRM software, look for the file extension, this should give you some idea of the more popular ones