[sqlite] invalid subselect is not detected ?

[Ken]

Is this an error or by design?
 create table ss( ssid, ss_value);
 create table s(id, s_value);
 
 insert into ss values (1,1234);
 insert into ss values (2,1234);
 
 insert into s values (1, 567);
 insert into s values (2, 567);
 insert into s values (3, 567);
 
 select id from s where id in ( select id from ss);
 
 returns 
 1
 2
 3
 
 Shouldn't the subselect fail since the id is not in the SS table ?
 
 select s.id from s where s.id in ( select ss.id from ss );
 returns:  SQL error: no such column: ss.id
 
 
 Thanks,
 Ken