SQL & PL/SQL :: How To Update Multiple Rows With Different Values Using Update Statement

I have one doubt about update command in sql. How to update the multiple rows with different values using update statment.

Eg:-

SQL> set linesize 500;
SQL> set pagesize 500;
SQL> select * from emp;
SQL> select empno,ename,sal from emp;
SQL> select empno,ename,sal from emp;

EMPNO ENAME SAL
---------- ---------- ----------
7839 KING 5000
7698 BLAKE 2850
7782 CLARK 2450
7566 JONES 2975
7654 MARTIN 1250

[Code]....

The above table contains 14 records. Now i would like to update the salary column with different values like

EMPNO SAL
===========
7839 18000
7698 20000
7782 5000
...
...
...
7934 25000

How to update above values with single update query.