21. What is .MDF File?
.MDF is Master data file it contains the actual information corresponding to a table.
22. What is .LDF File?
.LDF is a Log data file its contains the transaction information
23.Display the total salary being paid to all employees.
select sum(sal) as totalsalary from EMPTABLE;
24.Display the maximum, minimum and average salaries from EMPTABLE table.
select max(sal),min(sal),avg(sal) from EMPTABLE;
25.Display the maximum salary being paid to CLERK.
select max(sal) from EMPTABLE where job='CLERK';
26.Display the maximum salary being paid to depart number 20.
select max(sal) from EMPTABLE where deptno=20;
27.Display the minimum salary being paid to any SALESMAN.
select min(sal) from EMPTABLE where job='SALESMAN';
28.Display the average salary drawn by MANAGERS.
select avg(sal) from EMPTABLE where job='MANAGER';
29.Display the total salary drawn by ANALYST working in departs number 40.
select sum(sal) from EMPTABLE where job='ANALYST' and deptno=40;
30.Display depart numbers and total number of employees working in each department.
select deptno,count(deptno)from EMPTABLE group by deptno;