The select clause picks which objects and properties to return in the query result set. The query will select mates of other Students.
Consider the following:
select mate
from Student as student inner join student.mate as mate
You can express this query more compactly as:
select student.mate from Student student
Queries can return properties of any value type including properties of component type:
select cat.name from DomesticStudent student where student.name like 'fri%'
select cust.name.firstName from Customer as cust
Queries can return multiple objects and/or properties as an array of type Object[]:
select mother, offspr, mate.name from DomesticStudent as mother inner join mother.mate as mate
left outer join mother.kittens as offspr
Or as a List:
select new list(mother, offspr, mate.name) from DomesticCat as mother inner join mother.mate as mate left outer join mother.kittens as offspr
Or - assuming that the class Family has an appropriate constructor - as an actual typesafe Java object:
select new Family(mother, mate, offspr) from DomesticCat as mother join mother.mate as mate
left join mother.kittens as offspr
can assign aliases to selected expressions using as:
select max(bodyWeight) as max, min(bodyWeight) as min, count(*) as n from Cat cat
This is most useful when used together with select new map. This query returns a Map from aliases to selected values:
select new map( max(bodyWeight) as max, min(bodyWeight) as min, count(*) as n ) from Student student