有一个大表，大表由于录入时候有个空置，现在将空置赋予日期

1.该表很大，8t，由三列，其中create_time,现在要求修改成非空值，由于数据量比较大，因此采用分批来增加。

脚本如下
create or replace procedure PRC_UPDATE_CREATE_TIME is
start_num integer;
start_date date;
total number;
update_count integer;
per_loop_count integer;
begin
dbms_output.put_line('Start to batch update');

start_num := 1; -- start value of cycle
per_loop_count := 100; -- per cycle handle count
start_date := to_date('20100101', 'YYYYMMDD'); -- start date of create_time

/ get total number of the update records /
select count(1) into total from tmp_loan_file_data
where CREATE_TIME is null;

dbms_output.put_line('total number:');
dbms_output.put_line(total);

update_count := total/per_loop_count;
if (mod(total, per_loop_count) > 0) then
update_count := update_count + 1;
end if;

dbms_output.put_line('loop times:');
dbms_output.put_line(update_count);

/ Loop to update records /
while start_num <= update_count loop

dbms_output.put_line('loop seq :');
dbms_output.put_line(start_num);

merge into tmp_loan_file_data src_tab
using (select t.rowid as rid
from tmp_loan_file_data t
where t.CREATE_TIME is null
and rownum >=1
and rownum <= per_loop_count) sel_tmp
on (src_tab.rowid = sel_tmp.rid)
when matched then
update set CREATE_TIME = start_date;

start_num := start_num + 1;
start_date := start_date + 1;
commit;
end loop;

dbms_output.put_line('End batch update');
end PRC_UPDATE_CREATE_TIME;