I am developing a small web based centre management system for one organization using PHP,MySQL with Apache. This system is actually my course project. The organization have few centres located at different places.The headquarter(HQ) of the organization need to access all the centres data to generate report.The problem is that i didn't know how to design the database. Do i need separate database to store each centre's data or can i store all the information involving the HQ and centres in one database which will reside at the HQ main server?If i use many databases will that effect the processing speed of the query.Will there be any problem (regarding query processing speed) if a database for a web based system have more than 25 tables and i need to query multiple tables?
As a rule, you need one database per application, or applications. Since you are talking about one application, you will need only one database. You would normally create several tables, each table will relate to one "concept" in your application or will be used to store relational referencres between tables.