Question: I have a project to designing a website to search Zip codes on a digital map.
Somebody advised me to use PHP with postgreSQL or MySQL.

My professor wants me to tell him why I chose this for a mapping site.

The question is... Is there an expertise web language for GIS site ??
What is the difference if I use MySQL or MSsql or even Access if there is a connection to other remote database ??

Thanks

Answer: 
As for LAT/LON support in the databases, Access is going to give you pretty much zip-zero in terms of spacial SELECT(s). PostgreSQL has more established support for this, but MySQL has played catch up in the last year or so and has a working method of this in the latest versions. MySQL's version is apparently marginally faster than PostgreSQL, but lacks some of the more advanced spatial features therefore it's pretty much limited to finding records that match a certain range of coordinates. I can't speak for Microsoft's SQL solution, but for huge amounts of data you are going to want to stick with PostgreSQL/MySQL for performance--unless you want to go with Oracle, but even then the performance difference would be negligible. M$ SQL is abysmal in regard to performance and Access will never scale. 

Ideally, you should evaluate what functions each database engine has for dealing with geo-spacial data and choose which one performs the best and has the best features given your application's requirements.
PHP and MySQL are highly available, usually free, have a less-steep learning curve than most and offer (like many languages) exactly what you need.

I've done several mapping projects using google maps, location searches (based on LAT/LON or ZIP codes), interactive mappings and KML data. MySQL and PHP are more than capable.