find number of values that don't map

[tainks]

Hi i have two related tables, table A and table B. Table A has a column of index. Table B has a subset of that index, but each index can appear multiple times. 

How do I count the number of table A rows that do not map to table B? Thanks in advance!

[AlB · Accepted solution]

Hi @tainks

Try this to count the number index values in TableA but not in TableB

InA_NotInB =
COUNTROWS ( EXCEPT ( VALUES ( TableA[Index] ), VALUES ( TableB[Index] ) ) )

You can place the measure in a Card visual for instance