splitting column in many rows gives too many rows - oracle

Question

I am trying this statement
with value_table as
(select 1 id, '1/2/3' objnr from dual
union all
select 2, '4/5/6' from dual),
test as
(select id, objnr col from value_table where id in (1, 2))
select id, regexp_substr(col, '[^/]+', 1, level) result
from test
connect by level <= length(regexp_replace(col, '[^/]+')) + 1
order by 1
I want to get 6 rows
1 1
1 2
1 3
2 4
2 5
2 6
but I am getting the rows multiple times.
When I try it with just one id, it works without a problem.
As a workaround, I just made a loop for every single id, another solution is to use distinct, but that takes ages to execute, when I try it, with real data(over 1000 entries).
Can someone provide a more sophisticated solution?

Answer 1

This query is executed
with test as
(
select 1 id, '1/2/3' objnr from dual union all
select 2 id, '4/5/6' objnr from dual
)
select id, regexp_substr (objnr, '[^/]+', 1, rn) result
from test
cross
join (select rownum rn
from (select max (length (regexp_replace (objnr, '[^/]+'))) + 1 mx
from test
)
connect by level <= mx
)
where regexp_substr (objnr, '[^/]+', 1, rn) is not null
and id in (1, 2)
order by id,result ;
ID RESULT
1 1
1 2
1 3
2 4
2 5
2 6
If you use Oracle 11g, you can also use REGEXP_COUNT instead of the combination of REGEXP_REPLACE and LENGTH, which would look like this:
cross
join (select rownum rn
from (select max (regexp_count (objnr, '/') + 1) mx
from test
)
connect by level <= mx
)
to have outer join behaviour so made a slight variation as below:
with test as
(
select 1 id, '1/2/3' objnr from dual union all
select 2 id, '4/5/6' objnr from dual
)
select id, regexp_substr (objnr, '[^/]+', 1, rn) result
from test
left outer join (select rownum rn
from (select max (regexp_count (objnr, '/') + 1) mx
from test
)
connect by level <= mx
) splits
ON splits.rn <= length(regexp_replace (objnr, '[^/]+'))+1
and id in (1, 2)
order by id,result ;

Answer 2

try distinct as used below
with value_table as
(select 1 id, '1/2/3' objnr from dual
union all
select 2, '4/5/6' from dual),
test as
(select id, objnr col from value_table where id in (1, 2))
select distinct id, regexp_substr(col, '[^/]+', 1, level) result
from test
connect by level <= regexp_count(col, '[^/]+')
order by 1
tried with sqlfiddle http://sqlfiddle.com/#!4/03d80/14
EDIT:
If you don't want distinct try the below
with value_table as
(select 1 id, '1/2/3' objnr from dual
union all
select 2, '4/5/6' from dual),
test as
(select id, objnr col from value_table where id in (1, 2))
select id, regexp_substr(col, '[^/]+', 1, level) result
from test
connect by level <= regexp_count(col, '[^/]+')
and id = prior id
and prior dbms_random.value is not null
order by 1
which uses the model clause PRIOR the sqlfiddle link is http://sqlfiddle.com/#!4/03d80/31