连接来自多个表的多个列Oracle

Question

Sorry if this has been asked, searched around a bit and didn't find something quite like what I am after, but if it has please link.

I am using Oracle and trying to aggregate a result across multiple columns in multiple tables without using a temp table. Example below:

Table: USERS
--------------
ID | USER_NAME
--------------
1  | Bob
2  | Joe
3  | Mary

Table: PROJECT_USERS
----------------------------------
USER_ID | PROJECT_ID | ACCESS_TYPE
----------------------------------
1       |123         |8
1       |456         |9
1       |789         |10
2       |123         |10
2       |456         |9
2       |789         |8
3       |123         |9
3       |456         |10
3       |789         |10

I've been able to use LISTAGG for some success in doing things like finding the users who are in a particular project output into a single field using a query like:

SELECT
    LISTAGG(users.user_name, ',') WITHIN GROUP (ORDER BY users.user_name)
FROM
    users,
    project_users
WHERE
    project_users.user_id = users.id
    AND project_users.project_id = 123
GROUP BY ID
;

(apologies if the syntax is slightly off in the above, obscuring the actual structure and data for reasons so this isn't the exact query I'm using live) Which would output:

Bob,Joe,Mary

But what I'd like for output would be a combination of USERS.USER_NAME and PROJECT_USERS.ACCESS_TYPE aggregated in a similar format, perhaps with the two values separated by -

Bob-8,Joe-10,Mary-9

I can get the individual returns

SELECT users.user_name || '-' || project_users.access_type...

Returning

Bob-8
Joe-9
Mary-10

And was hoping I could then LISTAGG those results, but unfortunately haven't been able to get it to work. As mentioned earlier, a temp table is right out, for reasons I don't want to get into, though I'm sure that would make things a lot easier. Using a SELECT in FROM won't work, I don't think, as in the end I'd like to be able to use this in subqueries, and my understanding (and limited experience in trying it) is it wont iterate properly for each pass. Maybe I'm wrong, though, and just did it wrong.

Any suggestions?

Thanks!

Answer 1

It seems you want something like this. Not sure why you want it (in this case), but it illustrates the method you were asking about.

with
     users ( id, user_name ) as (
       select 1, 'Bob'  from dual union all
       select 2, 'Joe'  from dual union all
       select 3, 'Mary' from dual
     ),
     project_users ( user_id, project_id, access_type ) as (
       select 1, 123,  8 from dual union all
       select 1, 456,  9 from dual union all
       select 1, 789, 10 from dual union all
       select 2, 123, 10 from dual union all
       select 2, 456,  9 from dual union all
       select 2, 789,  8 from dual union all
       select 3, 123,  9 from dual union all
       select 3, 456, 10 from dual union all
       select 3, 789, 10 from dual
     )
-- End of test data (not part of the SQL query). 
-- Query begins below this line.
select project_id,
       listagg(user_name || '-' || to_char(access_type), ',')
           within group (order by user_name) as comma_sep_list
from   users u join project_users p on u.id = p.user_id
group by project_id
;

PROJECT_ID COMMA_SEP_LIST
---------- --------------------
       123 Bob-8,Joe-10,Mary-9
       456 Bob-9,Joe-9,Mary-10
       789 Bob-10,Joe-8,Mary-10

3 rows selected.