Hi,
The PHP is a great option for creating dynamic web gis application. PHP with ArcGIS Javascript API is a good combination.
By using PHP you can for example:
- create dynamic parts for your web gis application(Table of Contents, Attribute Tables e.tc)
- run spatial sql queries on the database level and add the results as graphics on the web app
- run attribute queries (faster than query or search Task) and add the results as graphics on the web app
- add security on your web gis app
- apply on the fly definition queries based on the user who is connected
- e.t.c
Panagiotis P.