How to make squential number by id in reference table

[EtaEfendi]

Hi, I want to make sequential number by id in ref table. In excel formula : if(a3=a2, a3+1,1) but I want use the formula in appsheet. 

[Marc_Dillon]

https://community.appsheet.com/t/serial-numbers-if-you-must/19325

[EtaEfendi]

Thank's @Marc_Dillon , I will try

[SkrOYC]

Your excel formula has no context here, we need to check your data to understand what are you trying to do.

The only thing that I can do is point you to this post

Serial Numbers, If You Must - Google Cloud Community

[EtaEfendi]

Main Table

Ref table.

The column [N0] will start at 1 depending coulumn [Id_K].

And how to change this excel formula : if(a3=a2, a3+1,1) in to Appsheet formula.