A DQL instance is a Boolean expression that selects objects from a perspective table. Logically, the query expression is evaluated against each perspective object; if the expression evaluates to “true”, the query selects the object.The query expression may include clauses that reference fields from objects that are linked to a perspective object. For example, if the perspective table is Person, the clause Manager.Name:John is true if a person’s Manager points to an object whose Name field includes the term John.