Split column into multiple rows in ORACLE based on static length of substring - sql

Question

I have seen multiple topics here for "Split column into multiple rows" but they all are based on some delimiter.
I want to split the column based on length in oracle.
Suppose i have a table
codes | product
--------------------------+--------
C111C222C333C444C555..... | A
codes are type VARCHAR2(800) and product is VARCHAR2(1).
Here in codes field we have many codes (maximum 200) which belongs to product A. and length of each code is 4 ( so C111, C222, C333 are different codes)
I want output of my select query like this-
code | product
---------------+-------
C111 | A
C222 | A
C333 | A
C444 | A
C555 | A
...
and so on.
please help me with this. Thanks in advance.

Answer 1

Here's yet another variation using regexp_substr() along with CONNECT BY to "loop" through the string by 4 character substrings:
SQL> with tbl(codes, product) as (
select 'C111C222C333C444C555', 'A' from dual union all
select 'D111D222D333', 'B' from dual
)
select regexp_substr(codes, '(.{4})', 1, level, null, 1) code, product
from tbl
connect by level <= (length(codes)/4)
and prior codes = codes
and prior sys_guid() is not null;
CODE P
-------------------- -
C111 A
C222 A
C333 A
C444 A
C555 A
D111 B
D222 B
D333 B
8 rows selected.
SQL>

Answer 2

Here is how I would do it. Let me know if you need more input / better explanations:
select substr(tt.codes,(((t.l-1)*4)+1),4) code,tt.product from tst_tab tt
join (select level l from dual connect by level <= (select max(length(codes)/4) from tst_tab)) t
on t.l <= length(tt.codes)/4
order by tt.product,t.l;
Some explanantions:
-- this part gives the numbers from 1 ... maximum number of codes in codes column
select level l from dual connect by level <= (select max(length(codes)/4) from tst_tab);
-- here is the query without the code extraction, it is just the numbers 1... numbers of codes for the product
select t.l,tt.product from tst_tab tt
join (select level l from dual connect by level <= (select max(length(codes)/4) from tst_tab)) t
on t.l <= length(tt.codes)/4
order by tt.product,t.l;
-- and then the substr just extracts the right code:
substr(tt.codes,(((t.l-1)*4)+1),4)
Set up of my test data:
create table tst_tab (codes VARCHAR2(800),product VARCHAR2(1));
insert into tst_tab values ('C111C222C333C444C555','A');
insert into tst_tab values ('C111C222C333C444C555D666','B');
insert into tst_tab values ('C111','C');
commit;

Answer 3

One option might be this:
SQL> with test (codes, product) as
2 (select 'C111C222C333C444C555', 'A' from dual union all
3 select 'D555D666D777', 'B' from dual
4 )
5 select substr(codes, 4 * (column_value - 1) + 1, 4) code, product
6 from test,
7 table(cast(multiset(select level from dual
8 connect by level <= length(codes) / 4
9 ) as sys.odcinumberlist))
10 order by 1;
CODE P
---- -
C111 A
C222 A
C333 A
C444 A
C555 A
D555 B
D666 B
D777 B
8 rows selected.
SQL>

Answer 4

Yet another a little bit different option of using recursive SQL to do this.
(To make it more concise I didn't add an example of test data. It could be taken from #Littlefoot or #Peter answers)
select code, product
from (
select distinct
substr(codes, (level - 1) * 4 + 1, 4) as code,
level as l,
product
from YourTable
connect by substr(codes, (level - 1) * 4 + 1, 4) is not null
)
order by product, l
P.S. #Thorsten Kettner made a fair point about considering to restructure your tables. That would be the right thing to do for sake of easier maintenance of your database in future