Oracle 11g hierarchical query needs some inherited data - oracle

Question

table looks kind of like:
create table taco (
taco_id int primary key not null,
taco_name varchar(255),
taco_prntid int,
meat_id int,
meat_inht char(1) -- inherit meat
)
data looks like:
insert into taco values (1, '1', null, 1, 'N');
insert into taco values (2, '1.1', 1, null, 'Y');
insert into taco values (3, '1.1.1', 2, null, 'N');
insert into taco values (4, '1.2', 1, 2, 'N');
insert into taco values (5, '1.2.1', 4, null, 'Y');
insert into taco values (6, '1.1.2', 2, null, 'Y');
or...
- 1 has a meat_id=1
- 1.1 has a meat_id=1 because it inherits from its parent via taco_prntid=1
- 1.1.1 has a meat_id of null because it does NOT inherit from its parent
- 1.2 has a meat_id=2 and it does not inherit from its parent
- 1.2.1 has a meat_id=2 because it does inherit from its parent via taco_prntid=4
- 1.1.2 has a meat_id=1 because it does inherit from its parent via taco_prntid=2
Now... how in the world do I query what the meat_id is for each taco_id? What is below did work until I realized that I wasn't using the inheritance flag and some of my data was messing up.
select x.taco_id,
x.taco_name,
to_number(substr(meat_id,instr(rtrim(meat_id), ' ', -1)+1)) as meat_id
from ( select taco_id,
taco_name,
level-1 "level",
sys_connect_by_path(meat_id, ' ') meat_id
from taco
start with taco_prntid is null
connect by prior taco_id = taco_prntid
) x
I can post some failed attempts to modify my query above but they're rather embarrassing failures. I haven't worked with hierarchical queries at all before beyond the basics so I'm hoping there is some keyword or concept I'm not aware I should be searching for.
I posted an answer myself down at the bottom to show what I ended up with ultimately. I'm leaving the other answer as accepted because they were able to make the data more clear for me and without it, I wouldn't have gotten anywhere.

Answer 1

Your inner query is correct. All you need is to pick only the rightmost number from the meat_id column of inner query, when flag is Y.
I have used REGEXP_SUBSTR function to get the rightmost number and CASE statement to check the flag.
SQL Fiddle
Query 1:
select taco_id,
taco_name,
taco_prntid,
case meat_inht
when 'N' then meat_id
when 'Y' then to_number(regexp_substr(meat_id2,'\d+\s*$'))
end meat_id,
meat_inht
from ( select taco_id,
taco_name,
taco_prntid,
meat_id,
meat_inht,
level-1 "level",
sys_connect_by_path(meat_id, ' ') meat_id2
from taco
start with taco_prntid is null
connect by prior taco_id = taco_prntid
)
order by 1
Results:
| TACO_ID | TACO_NAME | TACO_PRNTID | MEAT_ID | MEAT_INHT |
|---------|-----------|-------------|---------|-----------|
| 1 | 1 | (null) | 1 | N |
| 2 | 1.1 | 1 | 1 | Y |
| 3 | 1.1.1 | 2 | (null) | N |
| 4 | 1.2 | 1 | 2 | N |
| 5 | 1.2.1 | 4 | 2 | Y |
| 6 | 1.1.2 | 2 | 1 | Y |
Query 2:
select taco_id,
taco_name,
taco_prntid,
meat_id,
meat_inht,
level-1 "level",
sys_connect_by_path(meat_id, ' ') meat_id2
from taco
start with taco_prntid is null
connect by prior taco_id = taco_prntid
Results:
| TACO_ID | TACO_NAME | TACO_PRNTID | MEAT_ID | MEAT_INHT | LEVEL | MEAT_ID2 |
|---------|-----------|-------------|---------|-----------|-------|----------|
| 1 | 1 | (null) | 1 | N | 0 | 1 |
| 2 | 1.1 | 1 | (null) | Y | 1 | 1 |
| 3 | 1.1.1 | 2 | (null) | N | 2 | 1 |
| 6 | 1.1.2 | 2 | (null) | Y | 2 | 1 |
| 4 | 1.2 | 1 | 2 | N | 1 | 1 2 |
| 5 | 1.2.1 | 4 | (null) | Y | 2 | 1 2 |

Answer 2

This is what I've ended up with so far... after applying the logic in the accepted answer. I added a few more things so that I can join the result up against my meat table. the upper case could be optimized a little bit but I am so over this part of the query so.... it's going to have to stay for now.
select x.taco_id,
x.taco_name,
x.taco_prntname,
meat_id
,case when to_number(regexp_substr(meat_id,'\d+\s*$'))=0 then null else
to_number(regexp_substr(meat_id,'\d+\s*$')) end as meat_id
from ( select taco_id,
taco_name,
taco_prntname,
level-1 "level",
sys_connect_by_path(
case when meat_inht='N' then nvl(to_char(meat_id),'0') else '' end
,' ') meat_id
from taco join jobdtl on jobdtl.jobdtl_id=taco.jobdtl_id
start with taco_prntid is null
connect by prior taco_id = taco_prntid
) x
(do you ever wonder, when you read questions like this, what the real schema is? obviously I am not working on a taco project. or does it even matter as long as the general relationships and concept is preserved?)