[RESOLVED] Querying MySql through PHP...

[SpringBok]

Hey Guys!

Hey guys i need your help please.
i'm in a bit of confused. I'm building a vehicle rental system and I have created a database using MySQL that i'm successfully connecting to.

I have the following on my web page at the moment :

select Location (list/menu)

Rental Length(Days) (text field)

select Vehicle category (list/menu)

(Submit)

Hidden Field(See question below)

1-Locations are in the database and i can access database without problems
2-Rental length is where a user enters number of days(NB there's no field in database associated with this)
3-Vehicle categories are stored in the database and they are A-E and within the same table i've got a Daily_rate field where i've different rates for each category eg A=$40, B=55 etc

Now my problem:

How can i make the hidden field display results when user presses submit button.
The result should be category's daily rate * number of days entered.

Please Help!!

ps

Is it a good idea to have a Rental_length field stored in the database as well, all it's alright as it is?