Counting Instances of contact over a selectable date range, help!

[Anonymous]

I'm looking for a bit of help.  I'm new to using powerbi and come from a background on excel so as you can imagine, I'm having a little trouble adjusting.

I want to be able to select a date range and have a visual show me how often customers had to call me.

something like:-

1 call     =  "this many"

2 calls   =  "this many"

3 calls   =  "this many"

4 calls   =  "this many"

What I have so far is a table with all my call data with an identifier and date/time for each customer contact and a seperate table distinctly listing my identifiers.  I want to create a measure on the second table that will tell me how many times each of the distinct identifiers appears in the first table.  Idea being that when I select a date range on my visual, the measure on table 2 will adjust to count within that.  I feel as though I'm missing something very important though.

I've tried to do the following:-

 Measure = COUNTROWS( FILTER ('table1' , 'table1' [identifier] = 'table2' [identifier]))

This gives me the following error:

"A single value for column 'Account Number (Account)' in table 'Unique Accounts Table' cannot be determined. This can happen when a measure formula refers to a column that contains many values without specifying an aggregation such as min, max, count, or sum to get a single result."

I get a red underline under 'table2'[identifier] as well.

Anyone able to point me in the right direction with this one?

Thanks

[v-ljerr-msft · Accepted solution]

Hi @Anonymous,

Could you try the formula below to see if it works.

Measure =
IF (
    HASONEVALUE ( 'table2'[identifier] ),
    COUNTROWS (
        FILTER ( 'table1', 'table1'[identifier] = VALUES ( 'table2'[identifier] ) )
    ),
    COUNTROWS ( 'table1' )
)

Regards

[Anonymous]

Hi  v-ljerr-msft,

Thanks for for your suggestion.  This has worked but not the way I hoped.  When I come to filter by date on a visual using this measure, it doesn't re-adjust itself to look at only the data in table 1 between the 2 dates I select.  I'm maybe misunderstanding how measures work completely so I'll go back to the books and learn some more.

I can get the view I'm looking for now however if I were to now find away to create a new table from table 1 between date ranges which I'm sure I can work out.  I'll accept this one as answered and thank you once again for your help.

Kind Regards

Scottit