Field Calculation help needed

[nevhornsey]

I have a set of fields which I am trying to get totals from.

The idea is to add up how many prints are created at a certain size and price and then have a total cost.

The size and prices are as follows

A4 @ £25

A3 @ £50

A2 @ £75

so if there were 10 * A4 prints I would charge £250

At the moment I have a drop down menu for the size of prints in one field, a total number of prints in the next field and now I just need the total to be calculated based on what's in those fields.

i feel that the drop down menu may be causing too many problems but it is the neatest way of displaying the info, I just don't know how to set the different variables in the calculation.

any help would be appreciated

[John Mark Osborne]

Case(

size = "A4"; 25;

size = "A3"; 50;

size = "A2"; 75

) * NoPrints

[comment]

Generally, it's not a good idea to store prices in a calculation formula. When prices change (as they invariably do), your entire history is messed up.

You should have a table of prices, and lookup the price from there, based on the selected product/service. Then your calculation becomes Price * Quantity.

[nevhornsey]

I have decided to put my prices in seperate tables an d I will look them up.

The calculation from the previous reply looked very neat though.

As I look at it, does putting anything in " " mean that calculated part is processed and the " " is only displayed?

how does my calculated field know where to find " " ?

Also I looked for examples of calculations relating to similar circumstances. I found a sales ledger and inventory on two tables. the end result is the same to what I need.

I have basically set out my tables in the same way as the example and I have an equation that works ::

If( IsEmpty( Product Quantity ) ; 1 ; Product Quantity ) * Product Unit Price

If someone could break it down into lame english so I could understand why the equation is laid out this way I may not need to ask any more questions in the future. It looks to simple to be hard to understand but I just don't get 'If' or 'IsEmpty' or why there would be ' ; 1 ; ' in the middle

Edited October 12, 2006 by Guest
needed to ask more questions

[Søren Dyhr]

As I look at it, does putting anything in " " mean that calculated part is processed and the " " is only displayed?

Carefull here! NO! - The quotes means that the type is text and not interger ...when John put quotes around "A4" is he comparing strings of text with each other!

--sd