Count number of rows in another table with same ID

[Ramp85]

Hi All

I have a quite simple (I think) DAX question, that I hope you can help me with. Tried to find similar in the forum, without luck.

I hav two tables:

Table 1
Product	Customer	ReservationID
A	1	123
A	5	234
B	5	234
C	7	345
C	9	456
Table 2
Customer	ReservationID
1	123
2	123
3	123
4	123
5	234
6	234
7	345
8	345
9	456
10	567
11	567
12	678

There is a relation between the to tables, on Customer - Many-to-one.

Now:

If I have a filter on table 1 with Product = "A",

I wan't to create a meassure to count how many related customers in Table2 are on a reservation where another customer bought this product. 

So, in above example, if I filter on product "A", I can see that 6 customers are on a reservations that bought this product and thereby my desired result is "6".

If there is no filtering done on product level, I expect the result to be 11, as there is 11 customers on the reservations which have got any kind of product. (ie. reservation 234 bought two products, customer 10-12 is on reservations that are not present in table1)

I've been walking around, some Countrows, including a calculate with allselected, but I haven't been able to find the solution yet.

Looking forward to see your suggestions. Thanks in advance!

[sjoerdvn]

Try this:

# related customers = CALCULATE(DISTINCTCOUNT('Table 2'[Customer]), TREATAS(VALUES('Table 1'[ReservationID]), 'Table 2'[ReservationID]))

[Ramp85]

Dosn't change result when I filter on Products?

[sjoerdvn · Accepted solution]

I created the tables exactly as described and it works perfectly with a slicer or filter on product. So there is probably more to your model than you have described above.
Or did you create a computed column instead of a measure?

[Ramp85]

Hi Again

Sry, I must have set something wrong in the first try, now it works like a charm.
Thanks a lot!

Rgds. Claus

[Ramp85]

Hi

Thanks for your reply.

Work almost as it should. Everything is fine when choosing a single product. Only issue, is that if I choose two products. For example A & B I get 11 as a result, where I expect 8.

[v-yaningy-msft]

Hi, Ramp85

May I ask if this is the expected output you are looking for? Based on your description, I have created a measure to achieve the effect you are looking for. Following picture shows the effect of the display.

Measure:

RelatedCustomerCount =

IF (

    ISBLANK ( SELECTEDVALUE ( Table1[Product] ) ),

    COUNTROWS ( Table2 )

        - ( COUNT ( Table1[ReservationID] ) - DISTINCTCOUNT ( Table1[ReservationID] ) ),

    CALCULATE (

        COUNTROWS ( 'Table2' ),

        FILTER (

            'Table2',

            'Table2'[ReservationID] IN VALUES ( 'Table1'[ReservationID] )

        ),

        ALLSELECTED ( 'Table1' )

    )

)

If this does not work, could you please share some sample data without sensitive information and expected output.
How to provide sample data in the Power BI Forum - Microsoft Fabric Community

Best Regards,
Yang
Community Support Team

If there is any post helps, then please consider Accept it as the solution to help the other members find it more quickly.
If I misunderstand your needs or you still have problems on it, please feel free to let us know. Thanks a lot!

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