GROUP_ID
GROUP_ID() removes duplicate rows returned by a ROLLUP or CUBE.
GROUP_ID() doesn't accept any parameters.
If n duplicates exist, GROUP_ID returns numbers from 0 to n - 1.
CREATE TABLE EMP (EMPNO NUMBER(4) NOT NULL,
ENAME VARCHAR2(10),
JOB VARCHAR2(9),
SAL NUMBER(7, 2),
DEPTNO NUMBER(2));
INSERT INTO EMP VALUES (1, 'SMITH', 'CLERK', 800, 20);
INSERT INTO EMP VALUES (2, 'ALLEN', 'SALESMAN', 1600, 30);
INSERT INTO EMP VALUES (3, 'WARD', 'SALESMAN', 1250, 30);
INSERT INTO EMP VALUES (4, 'JONES', 'MANAGER', 2975, 20);
INSERT INTO EMP VALUES (5, 'MARTIN','SALESMAN', 1250, 30);
INSERT INTO EMP VALUES (6, 'BLAKE', 'MANAGER', 2850, 30);
INSERT INTO EMP VALUES (7, 'CLARK', 'MANAGER', 2850, 10);
INSERT INTO EMP VALUES (8, 'SCOTT', 'ANALYST', 3000, 20);
INSERT INTO EMP VALUES (9, 'KING', 'PRESIDENT',3000, 10);
INSERT INTO EMP VALUES (10,'TURNER','SALESMAN', 1500, 30);
INSERT INTO EMP VALUES (11,'ADAMS', 'CLERK', 1500, 20);
SQL> SELECT deptno, job, GROUP_ID(), SUM(sal)
2 FROM emp
3 GROUP BY deptno, ROLLUP(deptno, job);
DEPTNO JOB GROUP_ID() SUM(SAL)
---------- --------- ---------- ----------
10 MANAGER 0 2850
10 PRESIDENT 0 3000
20 CLERK 0 2300
20 ANALYST 0 3000
20 MANAGER 0 2975
30 MANAGER 0 2850
30 SALESMAN 0 5600
10 0 5850
20 0 8275
30 0 8450
10 1 5850
20 1 8275
30 1 8450
13 rows selected.
SQL>
A HAVING clause and GROUP_ID():
SQL> SELECT deptno, job, GROUP_ID(), SUM(sal)
2 FROM emp
3 GROUP BY deptno, ROLLUP(deptno, job)
4 HAVING GROUP_ID() = 0;
DEPTNO JOB GROUP_ID() SUM(SAL)
---------- --------- ---------- ----------
10 MANAGER 0 2850
10 PRESIDENT 0 3000
20 CLERK 0 2300
20 ANALYST 0 3000
20 MANAGER 0 2975
30 MANAGER 0 2850
30 SALESMAN 0 5600
10 0 5850
20 0 8275
30 0 8450
10 rows selected.
SQL>