DAX expression needed to create calculated column where vLookup kind of functionality is needed

Hi, Anonymous 

According to your description and sample data, I can clearly understand your requirement, I think you can try to create a calculated column like this to achieve your requirement:

Output =
var _parentdate=SELECTCOLUMNS(FILTER('Table',NOT(ISBLANK([Parent Data]))),"1",[Parent Data])
return
SWITCH(
    TRUE(),
    ISBLANK([Parent Data]),"Parent",
    [Unique Data] in _parentdate,"Parent",
    NOT([Unique Data] in _parentdate),"Child",
    BLANK())

And you can get what you want, like this:

You can download my test pbix file below

If this you still have a problem, you can post some sample data(without sensitive data) and your expected result.

How to Get Your Question Answered Quickly 

Thank you very much!

Best Regards,

Community Support Team _Robert Qin

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