How to calculate average value from data JPA - play-framework

[Tns publicbox]

Hello

I'm new to both Play framework and Java web programming. I try to
create my app follow what Wayne wrote in his book but I am not find
how to get average value from my data.

Someone please give me some example to get average value from data in
table.

Thank you.
Tns


I try this code
...
Query q = em.createQuery("select avg(w.totalcost) from Workorder w");
Double actual = (Double) q.getSingleResult();
...

I got this error message
The file /app/controllers/Application.java could not be compiled.
Error raised is : Query cannot be resolved to a type
In /app/controllers/Application.java (around line 191)
189: public static void doRecalcwocost(Long woid) {
190:
191: Query q = em.createQuery("select avg(w.totalcost) from Workorder
w");
192: Double avgcost = (Double) q.getSingleResult();

What is wrong?

/* Work Order Class */
package models;
import java.util.*;
import javax.persistence.*;
import play.db.jpa.*;

@javax.persistence.Entity
public class Workorder extends play.db.jpa.Model {
public Date wodate;
public String refid;
public String wosubject;
public String wotype;
public Date starttime;
public Date finishtime;
public Float totalcost = 0.0F;
@Column(length=4096)
public String wodetail;
public String user;
}

--

[Guillaume Bort]

Import javax.persistence.Query in your scope.

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Guillaume Bort, http://guillaume.bort.fr