MariaDB - Conjunction-Search in Many-to-Many - group-by

Question

I have problems to implement an "and-concatenated" search with many-to-many tables. I tried to present a simple example below. I use MariaDB.
I have a table with process. To the process a can assign persons and tags. There is a table for tags and a table for persons.
There a two many-to-many relationships: tags_to_processes and persons_to_processes.
example: Find all process with person 1 and person 2 and with tag 1 and 2. Result: process 1.
example: Find all process with person 1 and person 2 and with tag 2. Result: Process 1 and Process 2.
Thank you very much!
'processes' Table
+-----------+-------------------+
|process_id |process_name |
+-----------+-------------------+
|1 |Process 1 |
|2 |Process 2 |
|3 |Process 3 |
+-----------+-------------------+
'persons' table
+----------+------------+
|person_id |person_name |
+----------+------------+
|1 |Person 1 |
|2 |Person 2 |
|3 |Person 3 |
|4 |Person 4 |
|5 |Person 5 |
+----------+------------+
'tags' table
+----------+-----------+
|tag_id |tag_name |
+----------+-----------+
|1 |Tag 1 |
|2 |Tag 2 |
|3 |Tag 3 |
|4 |Tag 4 |
|5 |Tag 5 |
|6 |Tag 6 |
+----------+-----------+
'persons_to_processes' table
+----------+-----------+
|person_id |process_id |
+----------+-----------+
|1 |1 |
|2 |1 |
|3 |1 |
|4 |1 |
|5 |1 |
|1 |2 |
|2 |2 |
|4 |3 |
+----------+-----------+
'tags_to_processes' table
+----------+-----------+
|tag_id |process_id |
+----------+-----------+
|1 |1 |
|2 |1 |
|3 |1 |
|6 |1 |
|2 |2 |
|2 |3 |
+----------+-----------+

Answer 1

You can join persons_to_processes to persons, filter the resuults for the persons that you want and use aggregation:
SELECT ptp.process_id
FROM persons_to_processes ptp INNER JOIN persons p
ON p.person_id = ptp.person_id
WHERE p.person_name IN ('Person 1', 'Person 2')
GROUP BY ptp.process_id
HAVING COUNT(*) = 2 -- 2 persons
Similarly for the tables tags_to_processes and tags:
SELECT ttp.process_id
FROM tags_to_processes ttp INNER JOIN tags t
ON t.tag_id = ttp.tag_id
WHERE t.tag_name IN ('Tag 1', 'Tag 2')
GROUP BY ttp.process_id
HAVING COUNT(*) = 2 -- 2 tags
Finally, you can combine the 2 queries to get their common results with INTERSECT:
WITH
cte1 AS (
SELECT ptp.process_id
FROM persons_to_processes ptp INNER JOIN persons p
ON p.person_id = ptp.person_id
WHERE p.person_name IN ('Person 1', 'Person 2')
GROUP BY ptp.process_id
HAVING COUNT(*) = 2 -- 2 persons
),
cte2 AS (
SELECT ttp.process_id
FROM tags_to_processes ttp INNER JOIN tags t
ON t.tag_id = ttp.tag_id
WHERE t.tag_name IN ('Tag 1', 'Tag 2')
GROUP BY ttp.process_id
HAVING COUNT(*) = 2 -- 2 tags
)
SELECT process_id FROM cte1
INTERSECT
SELECT process_id FROM cte2;
See the demo.