About Advanced Native Query Support

EclipseLink provides an expression framework (also known as EclipseLink Native Query Support) with which you can express queries in a database-neutral fashion as an alternative to SQL when writing queries not supported by JPQL. EclipseLink expressions offer the following advantages over SQL when you access a database:

• Expressions are easier to maintain because the database is abstracted.

• Changes to descriptors or database tables do not affect the querying structures in the application.

• Expressions enhance readability by standardizing the Query interface so that it looks similar to traditional Java calling conventions.

• Expressions enable read queries to transparently query between two classes that share a relationship. If these classes are stored in multiple tables in the database, EclipseLink automatically generates the appropriate join statements to return information from both tables.

• Expressions simplify complex operations.

EclipseLink automatically generates the appropriate SQL from the specified expression.

The expression framework lets you work with expressions, database queries, call objects, and native queries.

• JPA Query Using a EclipseLink DatabaseQuery

  EclipseLink DatabaseQuery is a query object that provides a robust API for handling a variety of database query requirements, including reading and writing at the object level and at the data level.

• JPA Query Using a EclipseLink Call Object

  Using the DatabaseQuery method setCall, you can define your own EclipseLink Call to accommodate a variety of data source options, such as SQL stored procedures and stored functions.

• Named Parameters in a Native Query

  Using EclipseLink, you can specify a named parameter in a native query using the EclipseLink # convention.

• JPQL Positional Parameters in a Native Query

  Using EclipseLink, you can specify positional parameters in a native query using the Java Persistence Query Language (JPQL) positional parameter ?n convention to specify a parameter by number.

• JDBC-Style Positional Parameters in a Native Query

  Using EclipseLink, you can specify positional parameters in a native query using the JDBC-style positional parameter ? convention.