Native Queries in Netweaver 7.1

Question

Hello Forum,
how do i convince the EntityManager that a select statement used for a native query is actually a select statement?  I tried to issue an SQL statement starting with the keyword "select", containing a few parameters (i used a bare "?" to denote them, would this be correct?), a subselect, and some grouping operations, but upon calling getResultList(), the entity manager threw an Exception stating that the select statement was not a select statement.
Regards,
- Thomas

Answer 1

Rolf Paulsen wrote:
In native queries, according to the JPA spec, using positional parameters like :"?1", "?2",... is the only way to add parameters. Neither named parameters like ":foo" nor plain "?" are supported according to JPA 1.0 spec.
See JSR 220: Enterprise JavaBeansTM,Version 3.0, Java Persistence API, section 3.6.3 "Named parameters":
Only positional parameter binding may be portably used for native queries.
I only have (really good) experience with EclipsesLink where defining parameters in native queries works fine with ?1, ?2 like in the JPA spec. If in  SAP JPA parameters in native queries must be defined in the query string using plain ?, it will not be compliant with the spec.
SAP JPA passes the SQL string specified in a native query raw (unparsed) to the database. This means that SAP JPA does make any assumption with respect to the syntax required by the underlying database with respect to paramter markers. In standard SQL, a plain ? character is used as a parameter marker. Standard SQL does not understand ?1 nor :foo.
The only binding mechanism for parameter values in native queries supported by SAP JPA is positional (as in alignment with the spec). Example
Query query = em.createNativeQuery("SELECT LAST_NAME FROM EMPLOYEE WHERE FIRST_NAME = ?");
query.setParameter(1, "Tim");
Rolf Paulsen wrote:
> And in SAP JPA NetWeaver 7.30, we do not get fully transparent lazy loading like in EclipseLink but a weaker form using cglib with EntitiyManager.getReference(): Whenever you need lazy loading, you have to hand-code it into your code.
This is  a misundersanding. In 7.30, lazy loading of single-valued relationships is supported as an automatic mechanism. You do not need to programatically use getReference. However, as lazy loading of single-valued relationships has been introduced onyl with 7.30, you need enabled it explicitly in order to preserve a downward compatible behavior:
http://help.sap.com/saphelp_nw73/helpdata/en/68/f676ef36094f4381467a308a98fd2a/frameset.htm
-Adrian