I'm new to SQL Server and i have question:
Is it even possible to somehow use TIMESTAMPDIFF to calculate values from same column?
I mean some kind of loop that will calculate
TIMESTAMPDIFF(SECOND, Value.row1, Value.row2) and puts it in next column in row1.
Table has variable amount of rows (usualy 20k+, depending on query details).

Or any other idea how to calculate
TIMESTAMPDIFF if each data is in separate row, like in this excel example:

Now it's solved by feeding raw data into PowerBI/PowerQuery but it isnt perfect, not to mention tons of .csv/.xls files on shared disk and lack of those timestamps diff in SQL database