How to simplify this long if else statement?

[goodamr]

I have 3 products. All the products have the same price, I named it : price

Each product has a discount. I defined its variables as follows:
discount1, discount2, discount3

But there is a different tax for each product when the discount equals 100% (for example) as follows:
tax1, tax2, tax3

I wrote this code and it works well:

if discount1 = 100 and discount2 = 100 and discount3 = 100 then 
total_price = price - tax1 - tax2 - tax3
 
elseif discount2 = 100 and discount3 = 100 then
total_price = price - tax2 - tax3
 
elseif discount1 = 100 and discount3 = 100 then
total_price = price - tax1 - tax3
 
elseif discount1 = 100 and discount2 = 100 then
total_price = price - tax1 - tax2
 
elseif discount1 = 100 then
total_price = price - tax1
 
elseif discount2 = 100 then
total_price = price - tax2
 
elseif discount3 = 100 then
total_price = price - tax3
 
else
total_price = price
 
end if
 

But I need a simple and short code that do the same functionality because when new products are added, the code will be large and difficult to follow.

[jhardman]

total_price = price
If discount1 = 100 then
   total_price = total_price - tax1
End if
If discount2 = 100 then
   total_price = total_price - tax2
End if
If discount3 = 100 then
   total_price = total_price - tax3
End if

but it would be even better if it was arrays or something similar that you could loop through.

Jared

[Rabbit]

total_price = price - tax1 * (discount1 \ 100) - tax2 * (discount2 \ 100) - tax3 * (discount3 \ 100)

[goodamr]

@Jhardman: The problem is that the 3 condition can happen at the same time

[Rabbit]

His code accounts for that. So does mine. Although that depends on if the language you're using has an integer division operator. If not, you can use an integer conversion function or floor function.

[goodamr]

@Rabbit: Your statement is not what I need. If you can simplify it using arrays or for loop.

[Rabbit]

The results will be the same. Why do you have to use a loop?

[goodamr]

The issue is that: We subtract the (tax) variable from the (price) only when the (discount) equals 100

[Rabbit]

Exactly. Both jhardman's code and my code do what you want. Well, for mine you may need to use a different function if asp doesn't have an integer division operator but the concept is the same.

[goodamr]

Oh sorry, Jhardman's code is correct. But your code is not correct. suppose the discount is 50 so we don't have to subtract the tax from the price.

[Rabbit]

I know. It accounts for that.

[goodamr]

Also, suppose we have more than three variables for example
discount1, discount2,......, discount100 and tax1, tax2,...., tax100

I think it will be hard to maintain the code. I think we should have an array or a for loop, but how can I accomplish that. so any solution?

Thanks.

[Rabbit]

It sounds like you're having trouble understanding the formula. Let's break it down.

Given:

price = 1234
tax1 = 200
discount1 = 50
tax2 = 30
discount2 = 100
tax3 = 4
discount3 = 4
 
discount1 \ 100 = 50 \ 100 = 0
discount2 \ 100 = 100 \ 100 = 1
discount3 \ 100 = 100 \ 100 = 1
 
tax1 * (discount1 \ 100) = 200 * 0 = 0
tax2 * (discount2 \ 100) = 30 * 1 = 30
tax3 * (discount3 \ 100) = 4 * 1 = 4
 
price - tax1 * (discount1 \ 100) - tax2 * (discount2 \ 100) - tax3 * (discount3 \ 100)
price - 0 - 30 - 4 = 1234 - 0 - 30 - 4 = 1200

[Rabbit]

It sounds like you have the data in a database. What is the table structure?

[goodamr]

Yes, I have the data in a database. Here is the table structure:

student_id
Year
Price
Discount
Tax

I need to calculate the total price in all years and when the discoutn = 100 we subtrat the tax from the related price.

Thanks alot for helping me.

[Rabbit]

Can you give me some sample data?

[goodamr]

2100694445,2007,3200,100,150
2100694445,2008,3600,100,250
2100694445,2009,2200,100,50
2100694445,2010,4500,100,250

Thanks.

[Rabbit]

So then you don't actually have fields named tax1, discount1, etc.?

Then everything can be handled with a SQL statement. It depends on what SQL server you're using but for Microsoft SQL Server, I would do something like this

SELECT (SUM(price) - 
  SUM(CASE discount WHEN 100 THEN tax ELSE 0 END)
  ) AS total_price
FROM Table1

[goodamr]

I'm using Oracle 9

[jhardman]

Yeah, the query rabbit gave last is the best solution, you will need to make sure that syntax works in oracle, but otherwise, nice solution.

Jared