Subqueries are handled differently in sqlite3 and mysql?  
Rails generates the same SQL, databases return different results.
 
Using sqlite3:
----------------
 
>> Person.count
  SQL (0.2ms)   SELECT count(*) AS count_all FROM "people" 
=> 2
 
>> Person.all(:conditions => ['id NOT IN (?)', []])
  Person Load (0.9ms)   SELECT * FROM "people" WHERE (id NOT IN (NULL)) 
=> [#<Person id: 1, ...>, #<Person id: 2, ...>]
 
 
 
Using mysql:
----------------
 
>> Person.count
  SQL (0.0ms)   SELECT count(*) AS count_all FROM `people` 
=> 2
 
>> Person.all(:conditions => ['id NOT IN (?)', []])
  Person Load (0.0ms)   SELECT * FROM `people` WHERE (id NOT IN (NULL)) 
=> []