Build a Database

I want to create a database that will store data about every visitor session in my website. A. The data should include: 1. General data such as: -Date and time of visit -IP address -browser info -entry page URL -exit page URL -time spent in the website 2. Several designated columns, for certain url strings that the visitor might have arrived with: Example: A visitor arrives to "[login to view URL]", I want to strip down the "?source=partner1&adtype=banner" from the URL address bar (which can be done with a 302 redirect). Simultaneously, I want to store the "source=partner1" and "adtype=banner" values in the session data, and have in database designated columns named "referrer" and "type of ad", that would contain the values "partner1" and "banner" under that session׳s row. 3. Actions which the visitor took on the website, probably ‫ in the form of events (Note that this is dynamic data that should be updated while the session is ongoing) Example: I have a "more info" button that pops up a modal window. If I a visitor clicked that button, I want it to be indicated in the database. 4. Unique Identifying number: Each row in the database be given a unique identifying number or value (that should never repeat again). B. I am also strongly interested in the option of having that database communicate with another external data source, in the form of an automatic XML request every 30 minutes to that external source, and look up the aforementioned unique identifying number, and in case it finds it, it should import the content of another field which correlates with this number in that XML output (I have the relevant information and access keys in order to make a manual XML request from that source). C. General : - I am thinking about having such a database separately for each month of the year. - In general I am open to any of your advice and suggestions about the optimal way for building this whole project. - I would like to be able to view the database with Microsoft Excel so I can analyze it occasionally and draw conclusions about user behavior. - I need the database to be flexible in case I would like to add more data columns to it in the future. - I also want to know if it will be possible to manually edit and modify the database from a friendly excel-like interface (though without running over new data that was generated by new sessions while I was modifying older sessions). - I will also need a basic explanation about how the code works and what every line of code does, perhaps, in the form of comments within the code. - The database should not slow down the website. - It should be stored in a secured way to prevent it from being obtained by unauthorized sources.