JPA query language
The Java persistence query language (JPQL) is used to define searches against persistent entities independent of the mechanism used to store those entities. As such, JPQL is portable, and not constrained to any particular data store.
The Java persistence query language is an extension of the Enterprise JavaBeans query language, EJB QL, and is designed to combine the syntax and simple query semantics of SQL with the expressiveness of an object-oriented expression language:
| The application creates an instance of the javax.persistence.EntityManager interface.
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| The EntityManager creates an instance of the javax.persistence.Query interface, through its public methods, for example createNamedQuery.
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| The Query instance executes a query (to read or update entities).
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