是或否是不使用IF或CASE的sql查询结果

Question

Is there a way to make a query and return 'yes' or 'no' as an answer without the use of Flow Control operators?

The only solution I thought is:

select 'yes' as answer 
from blabla
where blabla

but this of course works only if the query found some results.

Answer 1

I like your blabla but don't understand your goal.

What is wrong with IF() statement or CASE WHEN ELSE END ?

If you like your blabla code you can continue the same logic:

select 'yes' as answer 
from blabla
where blabla.column=1
UNION
select 'no' as answer 
from blabla
where blabla.column<>1

and here is another tricky solution:

http://sqlfiddle.com/#!9/76065/24

SELECT @answer
FROM (
  SELECT @answer:='yes' 
  FROM blabla
  WHERE blabla.id=5
) y
RIGHT JOIN (SELECT @answer:='no') n
ON 1; 

Answer 2

You may want to COALESCE :

select coalesce(
    select 'yes' as answer 
    from blablaT
    where blabla,
    select 'no' as answer 
    from blablaT
    where not blabla) as result from dual;