On Mon, 28 Nov 2005 10:32:53 +0000, Richard Huxton wrote: > Haim Ashkenazi wrote: >> Hi >> >> I'm writing an application that calculates working hours for billing. >> there are three levels of billing. one for regular hours, one for >> evening/nights, and one for saturdays/holidays. >> >> My first decision is wether I make these calculations in a database view >> (If I understand correctly, it would be calculated only once - when >> creating the entry or modify it - or am I wrong?) > > Wrong. A view is just a way of transforming one query into another - it > re-runs the query every time. > > > or just put the >> regular working hours in the database, and calculate it in the application >> (and this way it would be calculated every time I view the page)? >> >> If I'm right and it's better to put it in the database, I really need help >> designing the database... (of-course it's an open-source project). >> >> my idea is to create one table that define default hours/days ranges for >> the three levels of billing, one table to define client specific ranges, a >> table with charging information (charge per hour for every level of >> billing for every customer), tables that define custommers, and job >> details and a final view that summerize everything. >> >> my main problem is how do I define an hour range from friday 15:00 to >> sunday 08:00, and how to create a function that compares the working hours >> with this range? > > Hmm - sounds to me like you either: > 1. Need to allow some time to go and learn the basics of relational > theory, and then some SQL and PostgreSQL admin. > 2. Find another team-member for your project who has these skills. > 3. Find another project that has solved the same problems. Join that > project or re-use elements (licence allowing). > > Now, #3 seems to be the best approach to me. Any timesheet/billing > application will have to deal with the sort of problem you're > describing, and it makes sense to learn what approaches others have tried. thanx, I was already told that a view gets calulated every time. in this case I'll write the logic in java (seems to be a nice chalange for a beginer :) ). Bye -- Haim
