Question

I have 3 tables with the following structure.

User

uid
username
password

Friend

id
uid
fid

Post

pid
uid
msg

I want to find all the posts that the friends of a user did. In SQL I extract that using this statement:

SELECT post.* FROM Post 
INNER JOIN Friend f ON f.fid = post.uid 
INNER JOIN User u ON f.uid = u.uid
WHERE u.uid = 1;

How can I convert this to JPQL?

Answer 1

JPQL queries entities and their associations, and you haven’t described them, so it’s a bit hard to say. But assuming a Post has a ManyToOne with a Friend, and a Friend has a ManyToMany with a User, the query would be:

select post from Post post
inner join post.friend friend
inner join friend.users user
where user.uid = 1