Question

On an Oracle 11g engine using PL/SQL
I have logic that runs like this

if (flag = Y) then 
   select id, flavor, color
   from menu
   where flavor in (1,2,3,4,5);
else 
   select 
   id, flavor, color
from 
   menu
   where flavor in (2,4,6);
end if;

I’m thinking using decode or case logic in the where clause? I’d like to have just one query that can handle both ‘flag’ values.

Answer 1

Can you just change it to use an OR? (assumed that flag it N if not Y, but may be NULL which will be treated as N)

  select 
   id, flavor, color
from 
   menu
   where 
        (flag = 'Y' and flavor in (1,2,3,4,5))
        or(nvl(flag,'N') = 'N' and flavor in (2,4,6)) ;

if you want to check for flag <> Y (in a similar fashion as @Crappy Coding Guy posted, but it can be NULL, changing

nvl(flag,’N’) = ‘N’

to

nvl(:flag,’N’) <> ‘Y’

will suffice