DB schema for packaging products/services together under a single price/offer

Question

I’m trying to “conceive” the business logic of this website that has many activities, that the users can build their “combo” and get discounts depending on their choices and how long they are willing to pay for their plan (1, 3, 6 and 12 month plans).

I’m having a hard time trying to come up with a solution, while keeping the database normalized and with proper relations, without having to resort to JSON-encoded data in the database fields. The system must stay generic enough to fit many businesses types that relies on plans/activities. I need to know how to structure my tables.

Scenario: For example, in case of a gym, will have bodybuilding, yoga, boxing, body pump. If the person choose bodybuilding and boxing, they will have a discount. If they add yoga, boxing and bodybuilding will keep the discount but will add the yoga without any discount to the price. If the person decides to pay 12 months upfront, they will get a bigger discount.

Bodybuilding + Body Pump

Bodybuilding..$70 | 28% discount
Body Pump.....$70 | 
Total........$100

1 month  - $100 / month
3 months - $ 91 / month
6 months - $ 75 / month

Bodybuilding + Body Pump + Yoga

Bodybuilding..$70 | 28% discount
Body pump.....$70 |
Yoga..........$90 | No discount
Total........$190   

1 month  - $190 / month
3 months - $171 / month
6 months - $158 / month

I’ll be using PHP and MYSQL but that doesn’t matter much, only the RDBMS part.

---

Edit for clarification: What I really looking for is a database schema for packaging products (or in this case services) together under a single price/offer. Each product must also exist in the system as a standalone product.

I still need the ability to report on sales (and profit) by product even if that product was sold as part of a package.

I would need the ability to report on package performance.

Answer 1

At a Minimum You need:

1. A Promo Header Table - Holds exactly what you get with the Promotion (Free item, free shipping, $$ off)
2. A Promo-Requirements Tables (I to meany to Promo's, Hold all the requirement if the promo) Each record is one Requirement, Requirements can be "must be and item of Brand X" or must be SKU 1234, or order total must be >50$ (When i did this is had a row type flag that told me what kid if Requirement it was.)
3. A module that is good a checking if an order meets a promotion's Requirements.

Unfortunately, I can't give you an exact ERD, because the promo conditions vary so much from business to business, so it's up to you make it as complex or simple as you need. For example, do you need Promos by SKU?, By Category, by subcategory?, by brand?, do you need to exclude certain SKUs?, brands? Category's? shipping locations?

Lastly make sure you make this thing easy to maintain and adjust, because just when you think you covered all your bases the business team will come up with some new crazier promo the no customer on earth will understand how to use.

---

EDIT: *Now that I better understand your question here what you need:*

Package Header Table and a Line Items Table, The Package Name and Description is stored on the header, The Lines hold the Items (including the Item prices when sold as part of that package).

You need a way to adding a Package to order. When that is done add then each item in the package as a regular line item but have a extra fields to specifies that the item is part of a Package and the PackageID.

It is then up to you to decide how you want to code the order Print out, Either just print a package total, so the customer doesn't know the line item prices, or print it normally but add with the package description.