CREATE OR REPLACE PROCEDURE ExportEmptyTable(param_tab varchar2)
Authid Current_User is
cursor tabCursor is
select table_name from user_tables;
sqlStr varchar2(200);
       begin
              if param_tab is not null THEN
              sqlStr:='alter table  '||param_tab||' allocate extent';
              execute immediate sqlStr;
              else
              for tab in tabCursor loop
              sqlStr:='alter table  '||tab.table_name||' allocate extent';
              execute immediate sqlStr;
              end loop;
              end if;
    end;