LAG with offset 1

Question

LAG with offset > 1

Accepted Answer

LAG(expr, offset) looks back offset rows in the window. For month 4, 2 rows back lands on month 2 with revenue=120. LAG(revenue, 1) would give month 3 (110). LAG(revenue) with no offset defaults to 1. You can also provide a third argument as the default for when no preceding row exists: LAG(revenue, 2, 0) would return 0 for months 1 and 2.