Thank you @Joseph Kambourakis​ 

The part that is not clear to me from the how to rework the part circled in the image above.

Even this part of the code does not work in databricks:

DATEADD(month, DATEDIFF(month, 0, DATEADD(month , 1 , EventStartDateTime)), 0)

Tried converting too but not sure which function(s) can replace those to get the same answers

Looking forward to more ideas