How does one code a matrix report in SQL using SUM & DECODE function?

Answer 1

   SELECT  *
    FROM  (SELECT job,
                  sum(decode(deptno,10,sal)) DEPT10,
                  sum(decode(deptno,20,sal)) DEPT20,
                  sum(decode(deptno,30,sal)) DEPT30,
                  sum(decode(deptno,40,sal)) DEPT40
             FROM scott.emp
            GROUP BY job)
    ORDER BY 1;

    JOB           DEPT10     DEPT20     DEPT30     DEPT40
    --------- ---------- ---------- ---------- ----------
    ANALYST                    6000
    CLERK           1300       1900        950
    MANAGER         2450       2975       2850
    PRESIDENT       5000
    SALESMAN                              5600