If you're only interested in the Ids of a given model, you can use the
on the query. The following code retrieves a list of Ids:
List<Long> ids = new QCustomer() .name.ilike("Rob%") .findIds();
SQL only selects the id from the table (even if you use the select clause)
select t0.id from Customer t0 where lower(t0.name) like 'Rob%'