SQL - merge two queries - sql

Question

I have the two below queries, the first query returns a list of externalId.
select e.externalId
from data_entity db
inner join assign_entity a on db.fk_assign = a.assignmentId
inner join exercise_entity e on a.fk_exercice = e.externalId;
The second query returns an internalId of each externalId returned by the first query:
select me.internal_id
from entity me
inner join entity_roles r on me.externalid = r.entity_externalid
where r.roles = 'c9237a21-f6da-4ebe-81b0-ddecd51da86b';
How can I merge the two queries in a single query to return for each externalId its internalId like this?

Answer 1

This should do what is required I think. Since there is no fiddle/data present, I can not test it.
with external as
(select e.externalId as externalId from data_entity db
inner join assign_entity a on db.fk_assign = a.assignmentId
inner join exercise_entity e on a.fk_exercice = e.externalId)
select distinct e.externalId, me.internal_id from entity me
inner join entity_roles r on me.externalid = r.entity_externalid
inner join external e on r.roles = e.externalId;

Answer 2

You can use EXISTS:
select me.internal_id, me.externalId
from entity me
inner join entity_roles r on me.externalid = r.entity_externalid
WHERE r.roles = 'c9237a21-f6da-4ebe-81b0-ddecd51da86b'
and exists (
select * from data_entity db
inner join assign_entity a on db.fk_assign = a.assignmentId
inner join exercise_entity e on a.fk_exercice = e.externalId
where e.externalId = me.externalId
);
Probably this query is simpler than what it is now, but based only on your pictures and queries this would do.
PS: Next time, please provide a good sample of your data tables. Pictures do not help much to anyone.

Answer 3

Without some data or a fiddle it is difficult to help, but I think this should work:
SELECT me.internal_id,
me.externalid
FROM entity me
INNER JOIN entity_roles r
ON me.externalid = r.entity_externalid
WHERE r.roles = 'c9237a21-f6da-4ebe-81b0-ddecd51da86b'
AND EXISTS (SELECT *
FROM data_entity db
INNER JOIN exercise_entity e
ON a.fk_exercice = e.externalid
INNER JOIN assign_entity a
ON db.fk_assign = a.assignmentid
WHERE me.externalid = e.externalid);