Oracle: Group Functions, Group Clause, Having Clause:

1. SELECT COUNT(*) FROM emp;

2. SELECT COUNT(hiredate) FROM emp;

3. SELECT COUNT(2) FROM  emp;

4. SELECT SUM(sal) FROM  emp;

5. SELECT AVG(sal) FROM emp;

6. SELECT MIN(sal) FROM emp;

7. SELECT MAX(sal) FROM emp;

8. SELECT STDDEV(sal) FROM emp;

9. SELECT VARIANCE(sal) FROM emp;

10. SELECT COUNT(*) FROM emp
      WHERE SAL < 4000;

12. SELECT COUNT(*) FROM emp
      WHERE HIREDATE > '11-Apr-1990';

13. SELECT SUM(sal) FROM emp
      WHERE ename LIKE'%A%';

14. SELECT  MAX(AMOUNT) FROM  ORDER
      WHERE SNUM IN(1002,1007)