Request Type SQL rule to populate a multiselect field

I'm trying to create a Field Change Rule to automatically add 3 values to a multiselect field based on the update of a simple single select field and I can't seem to get the SQL right.  I've tried the following two approaches, but both are invalid.  I'd prefer not to create a function.  Any suggestions.

Option 1:
select
'code1', 'value 1',
'code2', 'value 2',
'code3', 'value 3'
from dual

Option 2;

select
'code1#@#code2#@#code3'
'value 1#@#value 2#@#value 3'
from dual

Thanks,