Conecting tables together (Seller, Category, Items)

Hi im just asking for any advice possible.

Im working with Knack for few days now for school project and i dont know how to do folowing:

Ok what im trying to do is knack app for calculating items for custumer.

Let say i have 3 tables one is Seller, second one is categoryes for sellers and last one is items for each cathegory. It would look something like this

Seller: category items

Seller 1 --------> category 1 -------------> Item 1

Item 2

Item 3

category 2-----------------> item 1.1

item 1.2

Seller 2 ------------------> category 1.1 ................... And So On.................

Now problem is that i have done already three tables and i have connected them together but for me it show all sellers all categroyes and all items when i test it on app. How do i properly conect this together.Is there any formula needed to connect this together. Like i said im prety new with this program and any help would be apriciated.

Welcome.

OMG u are a life saver. THIS IS IT, this is exacly what i was looking for and it worked. Im soo green with this program but i see it has a lot functionality i just need to sit down and read basic structure of program.

All i had to do is change a few rules concerning connections and then SHOW option was available.

Thank you mate!

Can you check this out for

How to Create Dynamic Dropdowns in Forms

https://support.knack.com/hc/en-us/articles/226589108-How-to-Create-Dynamic-Dropdowns-in-Forms

and let me know if this what you are asking for.

Thank you for reply down are links to some screenshots of my own. All you need to know is

Prodajalci = Seller, Kategorija = Category, Izdelki = Items, and Naročila = Orders (Only for placing clients and date of order not inportant in this case). So if you look at last two pictures you will see that if i select Seller - Javor Trgovina then i should have only Category: Iveral available and when i select Iveral it should display only: bela iverka and Črna but for me it displays all

https://imgur.com/8hNJ28T

https://imgur.com/yMswtwr

https://imgur.com/hHBaZRj

https://imgur.com/TEBgr7A

https://imgur.com/bEU5bIS

https://imgur.com/l5gvt9C

https://imgur.com/Zt0LV8Z

https://imgur.com/hvwm7pt

https://imgur.com/os9v7he

Is the seller a USER (who can login and see his records)or just a table of SELLER (Just seller info).
I will help you with a short screencast how to do that.
Let me know.