• Post Reply
  • Bookmark Topic Watch Topic
  • New Topic

hibernate joining two tables

 
Jonathan LeeCh
Greenhorn
Posts: 4
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Hi, I am new to hibernate and maybe this had been answered before, but let me ask it again.

I am trying to return a join result between two tables and i read that by using the createAlias() i could associate the two tables together.

My two tables are Document and DocumentEntity and i am trying to use the entity_id(which is the primary key for DocumentEntity) and
using the doc_id from the DocumentEntity table to associate with the Document table to get me the doc_type from the Document table

Criteria crit = session.createCriteria(DocumentEntity.class)
.createAlias("Document", "d")
.add(Expression.eq("entity_id", entity_id)
.setProjection(Projections.projectionList()
.add(Projections.property("title"))
.add(Projections.property("d.doc_type"))
);

Is there anything I am missing out on, like whether do i need to specify the document.class anywhere so that the alias can be linked up

Replies are much appreciated thanks
 
Cameron Wallace McKenzie
author and cow tipper
Saloon Keeper
Posts: 4968
1
Hibernate Spring Tomcat Server
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Is there a foreign key relationship between the two tables?

-Cameron McKenzie
 
Jonathan LeeCh
Greenhorn
Posts: 4
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
oh yes, sorry for missing that out, the two tables are related by the field doc_id.
 
Cameron Wallace McKenzie
author and cow tipper
Saloon Keeper
Posts: 4968
1
Hibernate Spring Tomcat Server
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Just get the document object, and then call getDocumentEntity. It gets returned automatically if the foreign key relationship is mapped.

-Cameron McKenzie
 
Jonathan LeeCh
Greenhorn
Posts: 4
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
thanks Cameron for the reply, ok what if i want to get projections from two totally unrelated tables then?

i want to know how exactly does the createAlias() field helps in doing this.
 
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic