text: drop table if exists with_nullable;
  drop table if exists without_nullable;
  
  CREATE TABLE with_nullable
  ( timestamp UInt32,
    country LowCardinality(Nullable(String)) ) ENGINE = Memory;
  
  CREATE TABLE  without_nullable
  ( timestamp UInt32,
    country LowCardinality(String)) ENGINE = Memory;
  
  insert into with_nullable values(0,'f'),(0,'usa');
  insert into without_nullable values(0,'usa'),(0,'us2a');
  
  select if(t0.country is null ,t2.country,t0.country) "country" 
  from without_nullable t0 right outer join with_nullable t2 on t0.country=t2.country;
  
  drop table with_nullable;
  drop table without_nullable;
  
  