JPA update with a join - mysql

Question

I use spring-jpa with hibernate implementation.
I use mariadb
I try to do an update with a join.
My object structure
#Entity
public class Room {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long roomId;
#ManyToOne
#JoinColumn(name = "appartment_id")
private Appartment appartment;
}
#Entity
public class Appartment {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long appartmentId;
#OneToMany
#JoinColumn(name="appartment_id")
private Set<Room> roomList;
}
My sql query
update Room r1 set r1.available = :availability
where r1.roomId in (
SELECT r2.roomId
from Room r2
JOIN r2.appartment a1
WHERE a1.appartmentId = :appartmentId
tried also
update Room r1 set r1.available = :availability
where exists
( SELECT r2
from Room r2
JOIN r2.appartment a1
where a1.appartmentId= :appartmentId
)
I get this error
java.sql.SQLException: Table 'room' is specified twice, both as a target for 'UPDATE' and as a separate source for data
Seem like update and join with mysql seem impossible?

Answer 1

Everytime you get the unexpected token exception, look for syntax errors.
In your case the update query should look like this:
UPDATE Room r1
SET r1.available = :availability
WHERE r1.roomId in
( SELECT r2.roomId FROM Room r2 JOIN r2.appartment a1 WHERE a1.appartmentId = :appartmentId )
EDIT (follow-up issue):
Here you may find some help for your follow-up question
The accepted answer features a MySQL example on how to perform an update with a JOIN. I'm quite sure that's what you're after. Now it would look something like this:
UPDATE Room r1 JOIN r1.appartment a1
SET r1.available = :availability
WHERE a1.appartmentId = :appartmentId
try it with your dialect but if it doesn't work, the following one should do the trick:
UPDATE Room r1 SET r1.available = :availability WHERE r1.appartment.appartmentId = :appartmentId

Answer 2

IN ( SELECT ... ) has poor performance characteristics. Since you are looking at an UPDATE, I recommend a multi-table UPDATE. Or EXISTS is good -- but not that EXISTS. You have not tied the two instances of Room together; the UPDATE will change all or none of the rows!
Since you have not explained what the query is supposed to do, I cannot advise you on how to do it.