7.2. The from clause

The simplest possible EJB-QL query is of the form:

select c from eg.Cat c

select c from eg.Cat c

which simply returns all instances of the class eg.Cat. Unlike HQL, the select clause is not optional in EJB-QL. We don't usually need to qualify the class name, since the entity name defaults to the unqualified class name (@Entity). So we almost always just write:

select c from Cat c

select c from Cat c

As you may have noticed you can assign aliases to classes, the as keywork is optional. An alias allows you to refer to Cat in other parts of the query.

select cat from Cat as cat

select cat from Cat as cat

Multiple classes may appear, resulting in a cartesian product or "cross" join.

select form, param from Formula as form, Parameter as param

select form, param from Formula as form, Parameter as param

It is considered good practice to name query aliases using an initial lowercase, consistent with Java naming standards for local variables (eg. domesticCat).