Using Null in "OR" Filter in Complex Calculate Measure

[elmarcinpbi]

I am attempting to write a calculate measure in Power BI desktop that determines if a person was enrolled in program during a given month.  When a person is enrolled, the Enrolled Date is set, and the Disenrolled Date = null.  When they are disenrolled, the disenrolled date is set.  Since a person can enroll more than once, I cant just set a flag to indicate enrolled. 

I put together some syntax from other posts that looks like this:

Active Patients = CALCULATE (Countrows(PatientHistory),FILTER(PatientHistory,(PatientHistory[tkh_EnrolledDate]<=LASTDATE('Calendar'[Date])&&[tkh_DisenrolledDate]>=FIRSTDATE('Calendar'[Date])))||(PatientHistory[tkh_EnrolledDate]<=LASTDATE('Calendar'[Date])&&[tkh_DisenrolledDate]= BLANK() )))   

The editor is erroring on the last ), but I suspect it is something else.  Any ideas?

Thanks in advance.

[Sean · Accepted solution]

You have an extra closing ) before the || operator

You have 3 there when they should be 2 ))

[elmarcinpbi]

thank you, That fixed the syntax.

Since this table can have records that have enrolled date and disenrolled date with enrolled date, both, or none populated, I wanted to restrict the results set to only those that have ever been enrolled.

I created a calculated column that set a flag if Enrolled Date <> Blank() and used that as a filter in the visual.  Working now.