How to return 0 if table empty, 1 otherwise

Question

In postgreSQL, how can i return a table containing 0 if my table is empty and a table containing 1 if my table has rows?

I need to do it in SQL, not using any other language

Answer 1

Use:

SELECT CASE 
         WHEN EXISTS (SELECT * FROM foo LIMIT 1) THEN 1
         ELSE 0 
       END

EDIT: Added LIMIT 1 to speed up query.