orcl>
orcl>
orcl> var v1 number
orcl> exec :v1:=10

PL/SQL procedure successfully completed.

orcl> set autotrace on
orcl> select * from emp where deptno=:v1;

     EMPNO ENAME      JOB              MGR HIREDATE                 SAL       COMM     DEPTNO
---------- ---------- --------- ---------- ----------------- ---------- ---------- ----------
      7782 CLARK      MANAGER         7839 01-06-12 00:00:00       2450                    10
      7839 KING       PRESIDENT            09-11-12 00:00:00       5000                    10
      7934 MILLER     CLERK           7782 15-01-13 00:00:00       1300                    10


Execution Plan
----------------------------------------------------------
Plan hash value: 3956160932

----------------------------------------------------------------------------------
| Id  | Operation                 | Name | Rows  | Bytes | Cost (%CPU)| Time     |
----------------------------------------------------------------------------------
|   0 | SELECT STATEMENT          |      |     5 |   190 |     3   (0)| 00:00:01 |
|*  1 |  TABLE ACCESS STORAGE FULL| EMP  |     5 |   190 |     3   (0)| 00:00:01 |
----------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   1 - storage("DEPTNO"=TO_NUMBER(:V1))
       filter("DEPTNO"=TO_NUMBER(:V1))


Statistics
----------------------------------------------------------
          1  recursive calls
          0  db block gets
          7  consistent gets
          0  physical reads
          0  redo size
        974  bytes sent via SQL*Net to client
        419  bytes received via SQL*Net from client
          2  SQL*Net roundtrips to/from client
          0  sorts (memory)
          0  sorts (disk)
          3  rows processed

orcl>