accept tab prompt 'Enter table: ';
select * from &tab;

SQL> @a
Enter table: EMPLOYEE
old   1: select * from &tab
new   1: select * from EMPLOYEE

       ENO ENAME                DNO                      SALARY
---------- -------------------- -------------------- ----------
         1 Noor                 D10                     10000.5
         2 Ahmed                D20                    20000.75
         3 jaya                 D30                    15000.65
         4 hema                 D10                     10000.5
         5 rupa                 D20                    20000.75
         6 prabha               D40                    20000.75
         7 lalitha              D40                    12000.75
         8 vetri                D40                    12000.75

old   1: select * from &tab
new   1: select * from EMPLOYEE

SQL> set verify off
SQL> @run