How to create a menu in SQLPlus or PL/SQL?

Answer

Here is a SQL Plus script to do that:

prompt Please make a selection:
prompt 1: Do script a
prompt 2: Do script b
prompt 3: Do script c

accept selection prompt "Enter option 1-3: "

set term off

column script new_value v_script

select case '&selection.'
       when '1' then 'script_a'
       when '2' then 'script_b'
       when '3' then 'script_c'
       else 'menu'
       end as script
from dual;

set term on

@&v_script.

NB The 'menu' in the ELSE part of the case expression is the name of this script, so that it runs itself again when the user enters an invalid option.