Re: How to output record
To: comp.lang.java.databases
Ameen wrote:
I have mysql database has Nationality table of ID and Name fields. In
my Java application I am using entityManager to run a named query and
get the result as List, as follow:
// em is the entityManager.
// Nationality.getAllRecord is a named query created in Nationality
Entity Class,
// it only selects all record from Nationality table.
List qresult = em.createNamedQuery
(oNationality.getAllRecordo).getResultList();
It works fine and gets all the records. Even when I output the size of
result List using qresult.size() it gives the correct result.
Just I have one problem that is, how to output the data of each record
fields. I know that each qresult List item represent a record, and I
can get the specific record I need using qresult.get(int index)
function but how to reach the fields/column in a particular record .
I searched the Internet but I couldn't find any single example showing
that. Can any one help me please?
I think you are using the Java persistence API (and not JDBC or any of
the many other DBMS oriented APIs)
I've never used that API but Sun have a tutorial and the API
documentation is helpful.
qresult should be a List of Nationality instances. If you look at your
Nationality class (which I guess you annotated @Entity), there will be
accessor methods for the fields of the Nationality instances. Perhaps
getID() and getName():
List<Nationality> qresult = ...getResultList();
for (Nationality nationality: qresult) {
String id = nationality.getID();
String name = nationality.getName();
...
}
I've not seen an example using generics so you probably have to perform
a cast yourself.
List qresult = ...getResultList();
for (Object record: qresult) {
Nationality nationality = (Nationality) record;
String id = nationality.getID();
String name = nationality.getName();
...
}
Untested Caveat Emptor, Batteries not included.
http://java.sun.com/javaee/5/docs/tutorial/doc/bnbqa.html
http://java.sun.com/developer/technicalArticles/J2EE/jpa/
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