What script or database or both?
1. By and read this
Build Your Own Database Driven Website Using PHP & MySQL book.
2. The choice of databaseplattform is not unimportant. Today I got a master thesis from a student in Norway, that concludes that PostgreSQL is a more efficient database than MySQL on (nearly) all the tested tasks. That confirms my impression.
3. If you make a
connection class, you can use the same API on different databases. Then you can code independent of database plattform.
In case of large future requirements,
read this
"Today Gaia has a about 150 web servers behind our load balancer, and about 20 databases handling different features. Many of our old servers had been either de-commissioned or converted to storage servers. The new servers we're installing are all Opteron servers that are 4 times faster than older machines with the same power requirement. Since the ISP charges a lot for power, it's much more economical for us to upgrade.
We don't really believe in clustering. Rather we changed our database structure and the database abstraction layer to divide up data into seperate physical databases. That way we only need to add more of the same servers when upgrading, and we don't have to spend money on expensive clustering solutions and risk supporting a complex system.
We've just gotten another 20 database servers to replicate the existing ones for redundency. No replication is used for scalability or handling bandwidth. We still use MyISAM for small logs and data that doesn't get updated more than once a second, otherwise everything else is InnoDB".
The script is PHP.
Note, one of the easiest ways to learn a CMS system is implementing your own phpBB forum.
From a birds eye view, you learn to handle it and see how it is implemented. As you learn more and more code, e.g. by reading the above books and train, you will understand more of how it is done in that bulletin board code. You may also get a lot of "free" coding hints from that code.