Need to generate unique sequence number based on category

Question

Hi,
I have to update the NEW_NUMBER column  with unique number ,taking into category column consideration.
Here is the table structure and data.
{code}
create table sample(
CATEGORY VARCHAR2(100),
NUMBER   VARCHAR2(100),
NEW_NUMBER VARCHAR2(100))
{code}
{code}
insert into sample values('CAPACITOR','36858','');
insert into sample values('CAPACITOR','37858','');
insert into sample values('CAPACITOR','36958','');
insert into sample values('RESISTOR','46858','');
insert into sample values('RESISTOR','47858','');
insert into sample values('RESISTOR','46958','');
{code}
I have to update the NEW_NUMBER column  with unique number ,taking into category column consideration.
Output would be like this.
{code}
insert into sample values('CAPACITOR','36858','270-01-0000001');
insert into sample values('CAPACITOR','37858','270-01-0000002');
insert into sample values('CAPACITOR','36958','270-01-0000003');
insert into sample values('RESISTOR','46858','370-01-0000001');
insert into sample values('RESISTOR','47858','370-01-0000002');
insert into sample values('RESISTOR','46958','370-01-0000003');
{code}
If you can help to generate for one category,I will do it for other categories.
Thanks in advance.
Thanks,
Lak

Answer 1

Not sure how you came up with 270 and 370. But with what ever information you have provided this is what i came up with.
SQL> select * from sample;
CATEGORY   OLD_NUMBER           NEW_NUMBER
CAPACITOR  36858
CAPACITOR  37858
CAPACITOR  36958
RESISTOR   46858
RESISTOR   47858
RESISTOR   46958
6 rows selected.
SQL> merge into sample a
  2  using (
  3          select category
  4               , old_number
  5               , decode(category, 'CAPACITOR', '270', 'RESISTOR', '370')
  6                 || '-01-'
  7                 || lpad
  8                    (
  9                       row_number() over(partition by category order by old_number)
10                     , 7
11                     , '0'
12                    ) new_number
13            from sample
14        ) b
15     on (
16          a.category   = b.category and
17          a.old_number = b.old_number
18        )
19   when matched then
20      update set a.new_number = b.new_number;
6 rows merged.
SQL> select * from sample order by category, old_number;
CATEGORY   OLD_NUMBER           NEW_NUMBER
CAPACITOR  36858                270-01-0000001
CAPACITOR  36958                270-01-0000002
CAPACITOR  37858                270-01-0000003
RESISTOR   46858                370-01-0000001
RESISTOR   46958                370-01-0000002
RESISTOR   47858                370-01-0000003
6 rows selected.