How to setup a default value when defining (prompting) for a value?

Question

When I prompt the user in a SQL statement then I can declare a default value like in:
SELECT *
FROM all_users
WHERE username = nvl('&myvariable','SYSTEM');
But when I define a variable this does not work:
define tablename=nvl('&tablename','test123')
How can I setup a default value here?
Peter

Answer 1

Is there a way to define a default value DIRECTLY in SQLplus DEFINE command (and not later when the value is used in SQL statement)?no, there is not for DEFINE but you can use ACCEPT:
SQL> accept tablename prompt 'Enter value for table Name:' default EMP
Enter value for table Name:
SQL> select column_name
  2  from cols
  3  where table_name='&tablename';
OrderNumber=1234
COLUMN_NAME
EMPNO
ENAME
JOB
MGR
HIREDATE
SAL
COMM
DEPTNO
8 rows selected.Max
[My Italian Oracle blog| http://oracleitalia.wordpress.com/2010/02/07/aggiornare-una-tabella-con-listruzione-merge/]