Convert a string of ids into a string of equivalent names - sql

Question

I have this table (mock data) :
ID
Name
Location
1
Main
/
2
Photos
/1/3
3
Media
/1
4
Charts
/
5
Expenses
/4
The column Location is a string with ids that refer to that very table.
I'm looking for a query to convert ids into names, something like this :
ID
Name
Location
FullName
1
Main
/
/
2
Photos
/1/3
/Main/Media
3
Media
/1
/Main
4
Charts
/
/
5
Expenses
/4
/Charts
This is some mock data, in my real table I have more complex locations.
I'm not the owner of the table so I can't modify the schema. I can only read it.
Someone has an idea ?
Thank you very much
I've been exploring with this function : regexp_split_to_table
WITH flat_data AS (
SELECT DISTINCT
col.id col_id,
col.name col_name,
col.location col_full_loc,
regexp_split_to_table(col.location, '/') as loc_item
FROM collection col),
clean_data AS (
SELECT
col_id,
col_name,
col_full_loc,
CASE WHEN loc_item = '' THEN null ELSE loc_item::integer END loc_item,
ROW_NUMBER() over (partition by col_id, loc_item)
FROM flat_data
) select * from clean_data
So I've managed to have something like this :
| ID | Name | Location | AfterFunction |
| -- | -- | -- | -- |
| 1 | Main | / | |
| 2 | Photos | /1/3 | |
| 2 | Photos | /1/3 | 3 |
| 2 | Photos | /1/3 | |
| 2 | Photos | /1/3 | 1 |
| 3 | Media | /1 | |
| 3 | Media | /1 | 1 |
| 4 | Charts | / | |
| 5 | Expenses | /4 | |
| 5 | Expenses | /4 | 4 |
But at some point I lose the order of sublocation item
EDIT : table style

Answer 1

Outlook to the solution
ignore the first slash in the location to simplify the split and mapping (add it again at the end)
use regexp_split_to_table along with WITH ORDINALITY to preserve the order
outer join the location part to the original table (cast the idto textis it is int)
string_agg the location names to one string using the ordinality column and add the fixed slash prefix.
Query
with t2 as (
select * from t,
regexp_split_to_table(substr(t.location,2), '/') WITH ORDINALITY x(part, rn)
),
t3 as (
select t2.*, t.name part_name from t2
left outer join t on t2.part = t.id::text)
select
t3.id, t3.name, t3.location,
'/'||coalesce(string_agg(t3.part_name,'/' order by t3.rn),'') loc_name
from t3
group by 1,2,3
order by 1
gives result
id|name |location|loc_name |
--+--------+--------+-----------+
1|Main |/ |/ |
2|Photos |/1/3 |/Main/Media|
3|Media |/1 |/Main |
4|Charts |/ |/ |
5|Expenses|/4 |/Charts |
Below the result of the subqueries to illustrated the steps
-- T2
id|name |location|part|rn|
--+--------+--------+----+--+
1|Main |/ | | 1|
2|Photos |/1/3 |1 | 1|
2|Photos |/1/3 |3 | 2|
3|Media |/1 |1 | 1|
4|Charts |/ | | 1|
5|Expenses|/4 |4 | 1|
-- T3
id|name |location|part|rn|part_name|
--+--------+--------+----+--+---------+
1|Main |/ | | 1|Main |
2|Photos |/1/3 |1 | 1|Photos |
2|Photos |/1/3 |3 | 2|Photos |
3|Media |/1 |1 | 1|Media |
4|Charts |/ | | 1|Charts |
5|Expenses|/4 |4 | 1|Expenses |