text browser game

I'm pretty noobish at web coding / webdev.  I'm trying to figure out how I could write a browser game using only JavaScript on the client-side (ie. no browser plug-ins).  But I'm stuck on figuring out how to handle everything server-side.

The only thing I've thought of is to store everything in a SQL database, and just have the AJAX post some information to a PHP file that will take care of everything.  However, I'm wondering if there are other, better ways of doing this that I can't think of.  I'm also not sure about handling concurrent players because I haven't done very much with databases before, so I'm not sure whether I'll have to worry about race conditions or something.

Any ideas or advice would be appreciated.

>>6
- On completion of a level, a simple hypertext link appears (through javascript) that simply links to "game.cgi?level=" + (level + 1)

Not sure if I can explain this right. Essentially I want all of the game text (messages from the game, such as information about where you are, chat from other players, etc.) to appear in one edit box, streaming in real-time like IRC rather than just refreshing the page once every minute (like a shoutbox) or making the user click a link to go to the next page as you suggested.  Which is why I came up with AJAX, because I know I could do that with AJAX.  I don't know that I could do it any other way, but I'll take any suggestions.

>>2
The server-side language can be anything as well, why choose PHP?

Because I'm familiar with it.  Crappy reason, I know.  I should probably figure out a different language I could use for server-side scripting before I get into this.