Hallo @Reader1991,
und willkommen in der KNIME Gemeinschaft!
Use following nodes:
- Rank node with Laufzeitbeginn (Ascending order) as ranking attribute and Personalnummer as grouping attribute with Ranking Mode Ordinal. Will get rank column.
-
Math Formula node to subtract 1 from rank column (
$rank$ - 1). Make sure to have Convert to Int option checked. - Date&Time Shift node on Laufzeitbeginn with options Use Numerical → Numerical column → rank
Assumption is that same Personalnummer always have same Laufzeitbeginn.
Did you understand? If not someone or even I can (try to) translate it 
Br,
Ivan