A basic predicate compares two values. Basic predicates can be of two forms
expression-1 comparison-operator expression-2
expression-3 comparison-operator ( subselect )
The subselect must not return more than one value and the subselect cannot return a type of an Enterprise JavaBean (EJB) reference. Boolean types and reference types only support = and <> comparisons.
d.name='Java Development' e.salary > 20000 e.salary > ( select avg(e.salary) from EmpBean e)