Data size reducing

Question

Hi,
9iR2
Number of columns with NUMBER (18,5) have to get changed (modified) to NUMBER (13,2).
--Copy the original data (into new table)
- => UPDATE... to NULL
- MODIFY to NUMBER (13,2
I'm wondering how to get the old (copied) data back into resized columns?
What could be a solution to resize the data from 18,5 to 13,2?
Thx,

Answer 1

Not getting you properly ->
This would preserve your original column ordering.
satyaki>
satyaki>create table test_senti
  2      (
  3        col_a      varchar2(30),
  4        col_b      number(13,3),
  5        col_c      date
  6     );
Table created.
Elapsed: 00:00:04.85
satyaki>
satyaki>ed
Wrote file afiedt.buf
  1  insert into test_senti
  2     select col_a,
  3            col_b,
  4            col_c
  5     from (
  6            select 'AA' col_a,
  7                   12345.234 col_b,
  8                   sysdate col_c
  9            from dual
10            union all
11            select 'BB', 46578.345, sysdate from dual
12            union all
13            select 'CC', 57338.957, sysdate from dual
14*        )
satyaki>/
3 rows created.
Elapsed: 00:00:00.26
satyaki>
satyaki>commit;
Commit complete.
Elapsed: 00:00:00.04
satyaki>
satyaki>
satyaki>select * from test_senti;
COL_A                               COL_B COL_C
AA                              12345.234 21-OCT-08
BB                              46578.345 21-OCT-08
CC                              57338.957 21-OCT-08
Elapsed: 00:00:00.41
satyaki>
satyaki>
satyaki>update test_senti
  2     set COL_B = round(COL_B,2);
3 rows updated.
Elapsed: 00:00:00.16
satyaki>
satyaki>select * from test_senti;
COL_A                               COL_B COL_C
AA                               12345.23 21-OCT-08
BB                               46578.35 21-OCT-08
CC                               57338.96 21-OCT-08
Elapsed: 00:00:00.23
satyaki>
satyaki>
satyaki>commit;
Commit complete.
Elapsed: 00:00:00.05
satyaki>
satyaki>
satyaki>alter table test_senti add(col_d   number(13,2));
Table altered.
Elapsed: 00:00:00.24
satyaki>
satyaki>
satyaki>update test_senti
  2     set col_d = col_b
  3     ;
3 rows updated.
Elapsed: 00:00:00.04
satyaki>
satyaki>select * from test_senti;
COL_A                               COL_B COL_C          COL_D
AA                               12345.23 21-OCT-08   12345.23
BB                               46578.35 21-OCT-08   46578.35
CC                               57338.96 21-OCT-08   57338.96
Elapsed: 00:00:00.08
satyaki>
satyaki>
satyaki>commit;
Commit complete.
Elapsed: 00:00:00.03
satyaki>
satyaki>
satyaki>alter table test_senti drop column COL_B;
Table altered.
Elapsed: 00:00:01.18
satyaki>
satyaki>select * from test_senti;
COL_A                          COL_C          COL_D
AA                             21-OCT-08   12345.23
BB                             21-OCT-08   46578.35
CC                             21-OCT-08   57338.96
Elapsed: 00:00:00.09
satyaki>
satyaki>
satyaki>alter table test_senti rename column COL_D to COL_B;
Table altered.
Elapsed: 00:00:00.08
satyaki>
satyaki>select * from test_senti;
COL_A                          COL_C          COL_B
AA                             21-OCT-08   12345.23
BB                             21-OCT-08   46578.35
CC                             21-OCT-08   57338.96
Elapsed: 00:00:00.08
satyaki>Regards.
Satyaki De.