Question

Lets say I have query that gets following List Item Objects with Set of tags like this:

Item1{TagSet{tag1,tag2,tag3}}
Item2{TagSet{tag3,tag4,tag5}}
Item3{TagSet{tag6,tag7,tag8}}

Item1 Item2 Item3 are instances of Item object in List 
TagSet is Set Collection object

What HQL or SQL query would retrieve the List of Items having tag3 and from that result get list of all tags from thouse items that contain tag3 (not including tag3) eg. from the 3 items above?

Desired result would be:

TagSet{tag1, tag2, tag4, tag5}

Answer 1

You didn’t give us your schema, so I’m guessing here, but…

SQL:

select distinct *
from item
join tag on tag.item_id = item.id
where item.name = 'foo'
and tag.name != 'tag3'
and item.id in (select item_id from tag where name = 'tag3');

HQL:

entityManager
.createQuery("
    select t
    from Tag t
    where t.name != 'tag3'
    and t.item in (select t2.item from Tag t2 where t2.name = 'Tag3')
    and t.item.name = :name")
.setParateter("name", "foo")
.getResultList();

Then use tag.getItem() to get the Items for the tags returned.