If command

Anonymous , Try using

DAX
Anzahl Woche =
VAR _StartDate = SELECTEDVALUE('Geschäftskunden'[Startdatum])
VAR _EndDate = SELECTEDVALUE('Geschäftskunden'[Enddatum])
RETURN
IF (
ISBLANK(_EndDate),
DATEDIFF(_StartDate, TODAY(), WEEK),
DATEDIFF(_StartDate, _EndDate, WEEK)
)

Hello Anonymous,
Thank you for reaching out to the Microsoft Fabric Forum Community.

I have reproduced your scenario in Power BI Desktop using sample data, and I can confirm that the calculation is working as expected.

Summary of what I did:

• Created a sample table Geschäftskunden with both populated and blank Enddatum values.
• Used the following DAX formula in a calculated column to handle both cases correctly:

Anzahl Woche =

VAR _StartDate = 'Geschäftskunden'[Startdatum]

VAR _EndDate = 'Geschäftskunden'[Enddatum]

RETURN

IF(

    ISBLANK(_EndDate),

    DATEDIFF(_StartDate, TODAY(), WEEK),

    DATEDIFF(_StartDate, _EndDate, WEEK)

)

Result:
The column Anzahl Woche now shows the expected number of weeks:

• When Enddatum is blank, it uses Today().
• When Enddatum is present, it uses Enddatum.

I am attaching the sample .pbix file here for your reference so you can review and adapt it to your own dataset.

Thank you, bhanu_gautam & Ritaf1983 for sharing valuable insights.

If this information is helpful, please “Accept as solution” and give a "kudos" to assist other community members in resolving similar issues more efficiently.
Thank you.