select onwer,table_name,initial_extent 
from dba_tables where initial_extent is null order by owner;

select 'ALTER TABLE  '||table_name|| ' ALLOCATE EXTENT; ' 
from dba_tables where initial_extent is null order by owner;

  1* select count(*) from hotel
SQL> /

  COUNT(*)
----------
	 0

SQL> alter table hotel allocate extent;

Table altered.

SQL> select sum(bytes) from dba_extents where owner = 'USER1' AND SEGMENT_NAME = 'HOTEL';

SUM(BYTES)
----------
    131072

alter system set deferred_segment_creation=false;

SQL> show parameter deferred_segment_creatio

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
deferred_segment_creation            boolean     TRUE
SQL> alter system set deferred_segment_creation=false scope=both;

System altered.

SQL> show parameter deferred_segment_creatio

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
deferred_segment_creation            boolean     FALSE
SQL>

declare
   sql_str_v               varchar(2000);
begin
   for i in (
select owner, table_name 
from all_tables 
where segment_created = 'NO'
 and owner in (select username from all_users where user_id > 90) )
   loop
           sql_str_v := 'alter table '||i.owner||'.'|| i.table_name ||' allocate extent ';
           dbms_output.put_line(sql_str_v);
           execute immediate sql_str_v;
   end loop;
end;
/