Prevent Duplicate Values Valid_If

[AntonyCole1979]

Hi, I have 2 columns [Tested Date] (Which I have concatenated as text i.e “Jun 2019”) and column [Asset ID]. I would like to write a valid_if constraint within the [Asset ID] column to prevent anyone accidentally typing in the same [Asset ID] on the same date. Is this possible? If so how do I write the expression.

Thanks

Antony

[Bellave_Jayaram]

In Valid_If, put this:

NOT(IN([Asset ID], SELECT(TableName[Asset ID], [Tested Date]=[_THISROW].[Tested Date])))

[AntonyCole1979]

Excellent, thanks

Antony