text: create table R (A int);
  create table S (A int);
  create table T (A int);
  
  -- q1 (queries_null.js)
  select R.A from R where R.A not in (select S.A from S);
  -- Expected: []
  -- Got: []
  -- ok
  
  -- q2 (queries_null_1.js)
  select R.A from R where not exists (select * from S where S.A = R.A);
  -- Expected: [{"A":1},{"A":null}]
  -- Got: [{"A":null},{"A":1}]
  -- ok
  
  -- q3 (queries_null_2.js)
  select R.A from R except select S.A from S;
  -- Expected: [{"A":1}]
  -- Got: [{"A":1}]
  -- ok
  
  -- q4 (queries_null_3.js)
  select T.A,count(*) as c from T group by T.A;
  -- Expected: [{"A":null, "c":2},{"A":1,"c":1}]
  -- Got: [{"A":null,"c":{"$nat":2}},{"A":1,"c":{"$nat":1}}]
  -- ok
  