Hi! I'm building an app where the last depend...

[Tecnologia_Educ]

Hi! I’m building an app where the last dependent dropdown should return error if the value has been already used before. I’ve seen a way to prevent duplicates with list expressions but since it’s a dependent dropdown, it’s already using the ‘Valid_If’ field to reference another table. How can I accomplish setting a rule to invalidate values that have already been used?

The formula I’m using in Valid_If is: Base[Clave Participación (CP)]

Where ‘Base’ is the sheet refernced to filter this field (called simply ‘Clave’) based on the election on the previous column. And ‘Clave Participación (CP)’ is the unique value stored in the referenced table.

Thanks in advance

[Aleksi_Alkio]

Have you tried to use Suggested_Values and then you can use the validation independently?

[Tecnologia_Educ]

Is it using Suggested_Values for validation of duplicates or for referencing the filtered options?

[Aleksi_Alkio]

Try to use Base[Clave Participación (CP)] in Suggested_Values and then write something like AND(TRUE,NOT(IN([_THIS],TableName[Clave Participación (CP)]))) in Valid_If.