Table is specified twice, both as a target for 'UPDATE' and as a separate source for data

Question

I use spring-jpa with hibernate implementation. I use mariadb and I try to do an update subquery

My object structure

@Entity
public class Room {
  @         


        

Answer 1

This is a restriction in MySQL:-

http://dev.mysql.com/doc/refman/5.7/en/update.html

You cannot update a table and select from the same table in a subquery.

There is a fudge you can do sometimes do to hide the sub query in a a further level of sub query that might work. Something like this (not tested):-

UPDATE Room r1
SET r1.available = :availability
WHERE r1.roomId IN
    SELECT roomId
    FROM
    ( 
        SELECT r2.roomId 
        FROM Room r2 
        JOIN r2.appartment a1 
        WHERE a1.appartmentId = :appartmentId 
    )

Note that your query possibly has an error. In the sub query you are joining the table Room aliased as r2 to a table called appartment on a database called r2. Also your sub query does a JOIN without a join condition.

However you can quite possibly just do the join in the UPDATE statement without the need for a sub query:-

UPDATE Room 
INNER JOIN r2.appartment a1
ON Room.roomId = a1.roomId
SET r1.available = :availability
WHERE a1.appartmentId = :appartmentId