FIRST_VALUE and LAST_VALUE

Question

Accepted Answer

FIRST_VALUE returns the value from the first row in the window frame. With ORDER BY salary DESC, the first row is Alice (90000). Every row in the result gets Alice in the highest_paid column because the default frame is RANGE UNBOUNDED PRECEDING - so the first row is always Alice. LAST_VALUE behaves differently: with the default frame it returns the current row's value, not the final row. To get the true last value, you need ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING.