SELECT 
   [ { { DISTINCT | UNIQUE }  | ALL  } ]
   [ schema. ]
   { table | view | materialized view } .* | column | expr [ [ AS ] c_alias ]
FROM { table1 [, table2 ]...}
[ WHERE conditions ]
[ GROUP BY expr1 [, expr2]...]

FONCTION de GROUPE

Descriptions 

 
SQL> SELECT deptno, job, AVG(sal) AS "Moyenne Salaire"
  2  FROM emp
  3  GROUP BY deptno, job;

    DEPTNO JOB       Moyenne Salaire
---------- --------- ---------------
        20 CLERK                 950
        30 SALESMAN             1400
        20 MANAGER              2975
        30 CLERK                 950
        10 PRESIDENT            5000
        30 MANAGER              2850
        10 CLERK                1300
        10 MANAGER              2450
        20 ANALYST              3000

9 rows selected.

 
SQL> SELECT deptno, job, AVG(sal) AS "Moyenne Salaire"
  2  FROM emp
  3  WHERE job = 'CLERK'
  4  GROUP BY deptno, job;

    DEPTNO JOB       Moyenne Salaire
---------- --------- ---------------
        20 CLERK                 950
        30 CLERK                 950
        10 CLERK                1300

SQL>

 
SQL> SELECT AVG(sal) AS "Moyenne Salaire",
  2         COUNT(empno) AS "Nbre d'employes",
  3         COUNT(DISTINCT(deptno)) AS "Dept Distinct",
  4  FROM emp
  5  WHERE job = 'CLERK';

Moyenne Salaire Nbre d'employes Dept Distinct
--------------- --------------- -------------
         1037.5               4             3

SQL>

 
SQL> SELECT job,
  2         AVG(sal) AS "Moyenne Salaire",
  3         COUNT(empno) AS "Nbre d'employes",
  4         COUNT(DISTINCT(deptno)) AS "Dept Distinct"
  5  FROM emp
  6  GROUP BY job;

JOB       Moyenne Salaire Nbre d'employes Dept Distinct
--------- --------------- --------------- -------------
ANALYST              3000               2             1
CLERK              1037.5               4             3
MANAGER           2758.33               3             3
PRESIDENT            5000               1             1
SALESMAN             1400               4             1

SQL>