HQL (Hibernate Query Language)

• HQL Documentation (Red Hat) - A good place to start

• From the Hibernate reference (chapter 14)
  

• Joins (SQL) (INNER, OUTER - Wikipedia)
• inner join essentially combines the records from two tables A and B based on a given join predicate (considered default join)
  
• left outer join for tables A and B always contains all records of the "left" table (A)
• right outer join - Every record from the "right" table (B) will be in the joined table at least once.