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nhibernatejoinhql
Cadab
Cadab

Reputation: 467

NHibernate HQL - Joining

I want todo a simple join, well just comparing the ID's in two tables..

I have my Group Table, containing;

And i have my GroupMap Table containing;

My query takes a GroupMap.ItemID and is meant to return a list of groups that the itemID belongs to, in SQL I would have done this;

select Group.* from Group, GroupMap Where GroupMap.ItemID = '527' and Group.ID = GroupMap.GroupID;

This returns what i require, i just cant seem to replicate it in HQL, I thought it would have been quite trivial.

Thanks, James

Upvotes: 2

Views: 5514

Answers (2)

Vadim
Vadim

Reputation: 17957

You can use a theta join in hql

select g from Group g, GroupMap m Where m.ItemID = '527' and g.ID = m.GroupID

Upvotes: 8

Frederik Gheysels
Frederik Gheysels

Reputation: 56934

With a HQL, you do not think in terms of tables and relations between those tables, but in entities and associations between those entities.

So, if you have the Group and GroupMap classes (which you've mapped to your DB tables), you'll have to write your HQL something like this:

from Group as g inner join g.Maps as m where  m.ItemID = '527'

That is, supposing your Group entity has a collection of GroupMap entities ...

Upvotes: 3

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