Date Difference between last two entries, intersecting by Well ID
I am attempting to create a visualization that will give me the a look at the mean time bewteen failures. To do this, I need to first find the difference (months) between the last two Start Dates for each well. I know that it is a Datediff fucntion, and will require an OVER function so that the expression interects for each well...but everything I have tried has returned an error.
Basic chart attached for reference.