How do i perform a distinct statement in azure applications insights?

Question

I have a query that pulls a list of user engements of the form: Date, user name, campaign_id,

There is uniqueness in the campaign_id in a sense that a user clicks only once per day per campaign_id (campaign id cant be logged twice for the same user within a day)

My question is how do I pull a list of unique active users per month? A user can be logged more than once for different campaigns and different days.

customEvents 
| extend rTimeStamp = todatetime(customDimensions.timeStamp), 
         username = tolower(tostring(customDimensions.username)), 
         event = name, item_uid = tostring(customDimensions.itemId) 
| extend rTimeStamp = todatetime(substring(tostring(rTimeStamp), 0, 10)) 
| where event == 'click' 
| project rTimeStamp, username, event, item_uid
| summarize arg_min(rTimeStamp, *) by item_uid, username 
| summarize click_count = countif(event == 'click') by rTimeStamp, username, item_uid 
| order by rTimeStamp

Answer 1

Using the "distinct" operator:

... 
| distinct username

If you'd like a list of distinct users per month, also possible with summarize:

...
| summarize by username, bin(rTimeStamp, 30d)