Are there any mature and easy to use software development environments for Web/Database programming?
I reckon PHP/MySQL but that may be only because that's as far as I have gone.
If you've not touched rails, and you want something nice, I suggest django, uses a postgres backend by default, though supports multiple others
IMHO the problem with any of these is "lock in", and when they change their system you have to change with it. All us PHP developers got a nasty shock a few years ago when the "register globals" policy was changed, and we (basically) had to declare our variables in order to keep our code running. Long-term code needs to be able to run on any server under any configuration, and while this is impossible it's a lot more likely if it uses common and basic resources. I looked into Django and Dojo, and they're just - well - "big" (and Dojo seems to need Flash on the client to preserve state, and Flash has now been de-licensed for all BSD platforms except the Mac). Most effects can be created using basic HTML/CSS/Javascript - look, for example, at AHAH instead of Ajax.
Of course, for progress we need bleeding-edge programmers to try out all these new things.