Count if one column A is not blank, but other column B is blank

[Anonymous]

Hello, May I know what should I code based on below logic. 
Would like to know the number of Unique "PR Number" that is not blank, but the row of "PO number " is blank. 

[Anonymous]

Thank you so much ! it works ! Really appreciate that. 

[AilleryO · Accepted solution]

Hi,

This should do the trick :

Count of Unique PR w PO Blank = 
CALCULATE( DISTINCTCOUNT( TabPRPO[PR Num] ) , 
FILTER( TabPRPO, ISBLANK( TabPRPO[PO Num] ) && NOT ISBLANK(TabPRPO[PR Num]) ) )

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