SELECT empno,
       deptno,
       sal,
       FIRST_VALUE(sal) IGNORE NULLS
         OVER (PARTITION BY deptno ORDER BY sal) AS lowest_in_dept
FROM   emp;
---------------------------
SELECT empno, deptno, sal
	, FIRST_VALUE(sal) IGNORE NULLS OVER (PARTITION BY deptno ORDER BY sal) AS lowest_in_dept
FROM emp;