declare
    res varchar2(200);
    tabnam varchar2(200) := 'DWH_gate.T$TERMINAL';
    colnum int := 3;
    colnam varchar2 (32) := 'ID_AGENT';
begin
    EXECUTE IMMEDIATE 'select '||colnam||' from DWH_gate.T$TERMINAL' into res;
    dbms_output.put_line (res);
end;

declare
    type restype is table of varchar2 (64);
    res restype; 
    tabnam varchar2(200):= '&table_l' ;
    colnum int;
    colnam varchar2 (32) := &column_l;
begin
    select column_name into colnam
    from all_tab_columns
    where owner||'.'||table_name = upper (tabnam)
    and column_id = colnam;
    EXECUTE IMMEDIATE 'select '||colnam||' from '||tabnam bulk collect into res;
    for i in 1..res.count loop
        dbms_output.put_line (res(i)); 
    end loop;
end;