sql - list alias scope

i've only scholastic ( yesterday ) "exists" instead "in".

 bad
 name * list where nameid ( 
          name nameid othertable where otherdesc =  'somedesc' )      
 good
 name * list t where exists ( 
          name nameid othertable o where t.nameid = o.nameid otherdesc =  'somedesc' )      

and i have questions this:

1) reason i supposed was: "the reason since improved since wholly relating values returned instead building large list illusory results". does meant while initial subquery competence relapse 900 law second relapse wholly 1 ( approbation )?

2) past i have rdbms complainin: "only initial 1000 rows competence retrieved", second proceed solve problem?

3) range alias second subquery?... does alias wholly lives parenthesis?

for instance

 name * list t where exists ( 
          name nameid othertable o where t.nameid = o.nameid otherdesc =  'somedesc' )      
 
          name nameid othertable o where t.nameid = o.nameid otherdesc =  'someotherdesc' )      

that is, i same alias ( o list othertable ) second "exist" donation any problem initial exists? totally independent?

is something seer wholly associated current many rdbms?

thanks lot