SET @rn=0;
SET @last_deptno=-1;
SET @last_sal=-1;
SELECT deptno,
empno,
ename,
sal,
IF(@last_deptno = deptno, @rn := @rn + IF(@last_sal = sal,0,1), @rn := 1) AS dense_rank,
IF(@last_deptno = deptno, @last_sal := sal, @last_sal := -1) AS last_sal,
@last_deptno := deptno AS last_deptno
FROM EMP
ORDER BY deptno, sal;
+--------+-------+--------+------+------------+----------+-------------+
| deptno | empno | ename | sal | dense_rank | last_sal | last_deptno |
+--------+-------+--------+------+------------+----------+-------------+
| 10 | 7934 | MILLER | 1300 | 1 | -1 | 10 |
| 10 | 7782 | CLARK | 2450 | 2 | 2450 | 10 |
| 10 | 7839 | KING | 5000 | 3 | 5000 | 10 |
| 20 | 7369 | SMITH | 800 | 1 | -1 | 20 |
| 20 | 7876 | ADAMS | 1100 | 2 | 1100 | 20 |
| 20 | 7566 | JONES | 2975 | 3 | 2975 | 20 |
| 20 | 7788 | SCOTT | 3000 | 4 | 3000 | 20 |
| 20 | 7902 | FORD | 3000 | 4 | 3000 | 20 |
| 30 | 7900 | JAMES | 950 | 1 | -1 | 30 |
| 30 | 7654 | MARTIN | 1250 | 2 | 1250 | 30 |
| 30 | 7521 | WARD | 1250 | 2 | 1250 | 30 |
| 30 | 7844 | TURNER | 1500 | 3 | 1500 | 30 |
| 30 | 7499 | ALLEN | 1600 | 4 | 1600 | 30 |
| 30 | 7698 | BLAKE | 2850 | 5 | 2850 | 30 |
+--------+-------+--------+------+------------+----------+-------------+
14 rows in set (0.00 sec)
