Split one row into multiple in oracle - database

Question

I have a table which contains data something like this:
CREATE TABLE UDA_DATA
( uda VARCHAR2(20),
value_text VARCHAR2(4000)
);
insert into UDA_DATA values('Material_ID','PBL000129 PBL000132 PBL000130 PBL000131 PBL000133');
insert into UDA_DATA values('Material_ID','PBL000134 PBL000138 PBL000135 PBL000136 PBL000137');
insert into UDA_DATA values('Material_ID','PBL000125 PBL000128 PBL000126 PBL000124 PBL000127');
commit;
Now if we select the data from this table it will give the result something like this:
select * from UDA_DATA;
It gives result something like this:
But however I am expecting something like this:
Means it should break the value_text into two or more rows if the character length is more than 30. Also, uda column should have the suffix as 1,2..n
Not sure how to achieve this in a select query.

Answer 1

You could use recursive subquery factoring:
with rcte (uda, value, chunk_num, value_text) as (
select uda,
substr(value_text, 1, 30),
1,
substr(value_text, 31)
from uda_data
union all
select uda,
substr(value_text, 1, 30),
chunk_num + 1,
substr(value_text, 31)
from rcte
where value_text is not null
)
select uda || chunk_num as uda, value
from rcte;
UDA VALUE
-------------------- ----------------------------------------
Material_ID1 PBL000129 PBL000132 PBL000130
Material_ID1 PBL000134 PBL000138 PBL000135
Material_ID1 PBL000125 PBL000128 PBL000126
Material_ID2 PBL000131 PBL000133
Material_ID2 PBL000136 PBL000137
Material_ID2 PBL000124 PBL000127
The anchor member uses substr to get the first 30 characters as the value, and sets a chunk number which is always 1 for the anchor. It also gets the remains of the string after those first 30 characters have been removed, which may be null.
The recursive member does exactly the same, but working from the remains of the string as found by the previous iteration, and increments the chunk the number.
Finally the main query just gets all those extracted chunks, and appends the chunk number to the uda string.
You could use a hierarchical query if there is a unique key - the data you've shown doesn't have one though.
Your sample data doesn't have anything useful to order the results by. If your real table has a unique key you can use that by including it in both branches of the recursive CTE and then adding it to the final result as
order by unique_key, chunk_num
If there isn't on then you can get closer to your expected result by introducing a dummy key in the anchor member, e.g. using row_number() or the simpler rownum:
with rcte (rn, uda, value, chunk_num, value_text) as (
select rownum,
uda,
substr(value_text, 1, 30),
1,
substr(value_text, 31)
from uda_data
union all
select rn,
uda,
substr(value_text, 1, 30),
chunk_num + 1,
substr(value_text, 31)
from rcte
where value_text is not null
)
select uda || chunk_num as uda, value
from rcte
order by rn, chunk_num;
UDA VALUE
-------------------- ----------------------------------------
Material_ID1 PBL000129 PBL000132 PBL000130
Material_ID2 PBL000131 PBL000133
Material_ID1 PBL000134 PBL000138 PBL000135
Material_ID2 PBL000136 PBL000137
Material_ID1 PBL000125 PBL000128 PBL000126
Material_ID2 PBL000124 PBL000127