createQuery

CreateQuery is a common method in data access layers used to construct executable queries from either a textual query or a query builder object. It is found in various ORM and database access frameworks and typically returns a Query or TypedQuery object that can be further configured and executed.

In practice, createQuery accepts input that defines what to retrieve or manipulate. This input can be a string written in a query language such as SQL, JPQL, or HQL, or a builder-based representation that programmatically specifies the query structure. Once a query object is created, developers usually bind parameters to placeholders to prevent injection attacks, specify result types, and optionally apply pagination or limits before execution.

Common usage patterns include creating a query from a string, setting parameters, and invoking methods to obtain results, such as getResultList or getSingleResult. Some frameworks also provide createQuery overloads that accept a criteria object or a pre-defined named query. The returned query may be executed directly against the database or transformed into a typed or mapped result set.

Key considerations include ensuring parameter binding is used to reduce security risks, understanding whether the framework uses native SQL or a higher-level query language, and being aware of differences in behavior between native and non-native queries, such as how results are mapped to entities. Performance aspects like query caching and proper indexing also influence how createQuery is used in multi-tenant or high-traffic applications.

Example: EntityManager em; Query q = em.createQuery("SELECT u FROM User u WHERE u.active = :active"); q.setParameter("active", true); List<User> users = q.getResultList();