How to set default value for missing substitution parameter

Question

I'm calling a procedure in a script and passing variables like this:

@@./procedudure.sql 'var1' 'var2' 'var3'

In the procedure I'm using the values like this:

DEFINE variable1 = '&1'
DEFINE variable2 = '&2'
DEFINE variable3 = '&3'
...
insert into TABLE (id, text) values ('&varibale1', '&variable2&variable3')

I want to be able to call the procedure with only two parameters instead of 3 so that the last one is replaced with empty string. But when I call it like this, I get this prompt:

Enter value for 3: 

I've also tried to use the parameters like this, but with the same result:

DEFINE variable2 = '&2' || '&3'

I've found this page for using prompt for missing variable, but couldn't find anywhere how to set a default value: https://blogs.oracle.com/opal/entry/sqlplus_101_substitution_varia#9_14

As you can see from the code, I want the last parameters to be concatenated. This should be a workaround for 240-character limit.

Answer 1

Well yes I see it's old but... until now, unanswered!

OP, this is what you're looking for but it's not exactly simple! I originally spotted the technique on Tanel Poder's website but not sure if he came up with it or not.

Anyway, here I'm using it to setup defaults in case warning and critical limits are not passed in to the script.

rem setup default values
def DEFAULT_WARN_LEVEL='97'
def DEFAULT_CRIT_LEVEL='99'

rem trick to assign values to &1 and &2 so that SQL*Plus does not ask
col warn_level new_value 1
col crit_level new_value 2
select null warn_level
,      null crit_level
from   dual
where  1=2
/

rem if values were passed in, use them, if not, use the defaults
select nvl('&1','&DEFAULT_WARN_LEVEL') warn_level
,      nvl('&2','&DEFAULT_CRIT_LEVEL') crit_level
from   dual
/
rem the values, either passed in or defaults are now in &1 and &2

rem put the values in meaningful variables
def warn_level='&1'
def crit_level='&2'