set ver on/off

set   verify(或ver)   on/off可以设置是否显示替代变量被替代前后的语句

SQL> set verify on
SQL> select &num from dual;
Enter value for num: 1
old   1: select &num from dual
new   1: select 1 from dual

         1
----------
         1

SQL> set verify off
SQL> select &num from dual;
Enter value for num: 1

         1
----------
         1

SQL>