Duplicate Entries

[ouafaa]

I have a list sharepoint online, I want to prohibit the entry of duplicates on 3 columns. for example: I have a list with the following columns: year, month, customer, ... I want to prohibit the entry of the same values ​​of (year, month, customer) on 2 different lines. how can we do that?

thanks

[#2]

One way it comes to my mind is to customize the list forms with PowerApps so you can code this business rule in PowerApps

[#3]

Was about to say the same thing. Here are a couple video's to help you get started.

SharePoint Powerapp integration: https://www.youtube.com/watch?v=BnYe_7fpZRM&t=1s
And
Form validation: https://www.youtube.com/watch?v=vOzvZI6tmzQ

The Price field is the one to pay attention too from this video as it uses && which you would basically do a check for ColumnA && ColumnB && ColumnC etc.

[#4]

Hi,

thank you for your answer

so, isn't there a way to do it without using powerapps ?

Thanks