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Using a Column Multiple Times in a GROUP BY Clause

SQL> CREATE TABLE employee(   2    employee_id INTEGER,   3    division_id CHAR(3),   4    job_id CHAR(3),   5    first_name VARCHAR2(10) NOT NULL,   6    last_name VARCHAR2(10) NOT NULL,   7    salary NUMBER(6, 0)   8  ); Table created. SQL> SQL> insert into employee (EMPLOYEE_ID,division_id,JOB_ID,FIRST_NAME,LAST_NAME,SALARY)   2                 values(1, 'BUS','PRE','James','Smith','800000'); 1 row created. SQL> insert into employee (EMPLOYEE_ID,division_id,JOB_ID,FIRST_NAME,LAST_NAME,SALARY)   2                 values(2, 'SAL','MGR','Ron','Johnson','350000'); 1 row created. SQL> insert into employee (EMPLOYEE_ID,division_id,JOB_ID,FIRST_NAME,LAST_NAME,SALARY)   2                 values(3, 'SAL','WOR','Fred','Hobbs','140000'); 1 row created. SQL> insert into employee (EMPLOYEE_ID,division_id,JOB_ID,FIRST_NAME,LAST_NAME,SALARY)   2                 values(4, 'SUP','MGR','Susan','Jones','200000'); 1 row created. SQL> insert into employee (EMPLOYEE_ID,division_id,JOB_ID,FIRST_NAME,LAST_NAME,SALARY)   2                 values(5, 'SAL','WOR','Rob','Green','350000'); 1 row created. SQL> SQL> select * from employee; EMPLOYEE_ID DIV JOB FIRST_NAME LAST_NAME      SALARY ----------- --- --- ---------- ---------- ----------           1 BUS PRE James      Smith          800000           2 SAL MGR Ron        Johnson        350000           3 SAL WOR Fred       Hobbs          140000           4 SUP MGR Susan      Jones          200000           5 SAL WOR Rob        Green          350000 SQL> SQL> SQL> --Using a Column Multiple Times in a GROUP BY Clause SQL> SQL> --You can use a column multiple times in a GROUP BY clause, which can enable you to reorganize your data or report on different groupings of data. For example, the following query contains a GROUP BY clause that uses division_id twice, once to group by division_id and the second in a ROLLUP: SQL> SQL> SELECT division_id, job_id, SUM(salary)   2  FROM employee   3  GROUP BY division_id, ROLLUP(division_id, job_id); DIV JOB SUM(SALARY) --- --- ----------- BUS PRE      800000 SAL MGR      350000 SAL WOR      490000 SUP MGR      200000 BUS          800000 SAL          840000 SUP          200000 BUS          800000 SAL          840000 SUP          200000 10 rows selected. SQL> SQL> SQL> SQL> drop table employee; Table dropped. SQL>