Question

How to get value of some fields in a native query (JPA)?

For example I want to get name and age of customer table:

Query q = em.createNativeQuery("SELECT name,age FROM customer WHERE id=...");

Note: I don’t want to map results to entities. I just want to get the value of the field.

Thanks

Answer 1

A native query with multiple select expressions returns an Object[] (or List<Object[]>). From the specification:

3.6.1 Query Interface

…

The elements of the result of a Java
Persistence query whose SELECT clause
consists of more than one select
expression are of type Object[]. If
the SELECT clause consists of only one
select expression, the elements of the
query result are of type Object. When
native SQL queries are used, the SQL
result set mapping (see section
3.6.6), determines how many items (entities, scalar values, etc.) are
returned. If multiple items are
returned, the elements of the query
result are of type Object[]. If only a
single item is returned as a result of
the SQL result set mapping or if a
result class is specified, the
elements of the query result are of
type Object.

So, to get the name and age in your example, you’d have to do something like this:

Query q = em.createNativeQuery("SELECT name,age FROM customer WHERE id = ?1");
q.setParameter(1, customerId);
Object[] result = (Object[])q.getSingleResult();
String name = result[0];
int age = result[1];

References

• JPA 1.0 specification
  • Section 3.6.1 “Query Interface”
  • Section 3.6.6 “SQL Queries”