Java Persistance: Question about query within inheritance class

In father class here is the annotation:
@Entity
@Table(name = "CONTENT_MEDIA")
@Inheritance(strategy=javax.persistence.InheritanceType.JOINED)
@DiscriminatorColumn(name="CONTENT_TYPE", discriminatorType=javax.persistence.DiscriminatorType.INTEGER)
@DiscriminatorValue("4")
In son class here is the annotation and query:
@Entity
@Table(name = "ISBN_BOOK")
@DiscriminatorValue("1000001")
@NamedQueries( {
@NamedQuery(name = "ISBN_BOOK.findViaISBN", query = "SELECT g FROM ISBNBook g WHERE g.ISBNnumber = :isbn")
When I do the query, the result is:
Internal Exception: org.apache.derby.client.am.SqlException: Comparisons between 'INTEGER' and 'CHAR' are not supported.Error Code: -1
Call:SELECT t0.CONTENT_ID, t0.CONTENT_TYPE, t0.OBTAIN_DATE, t0.SEARCH_TIMES, t0.LAST_SEARCH_DATE, t1.CONTENT_ID, t1.BOOK_NAME, t1.AUTHOR, t1.ISBN_NUMBER, t1.CURRENT_LOCATION FROM CONTENT_MEDIA t0, ISBN_BOOK t1 WHERE ((t1.ISBN_NUMBER = CAST (? AS VARCHAR(32672) )) AND ((t1.CONTENT_ID = t0.CONTENT_ID) AND (t0.CONTENT_TYPE = '1000001')))
bind => [AAA]
The problem is: t0.CONTENT_TYPE = '1000001'. I have set the column to Integer, why the JPA use the char?
Can anyone solve the problem for me?

In father class here is the annotation:
@Entity
@Table(name = "CONTENT_MEDIA")
@Inheritance(strategy=javax.persistence.InheritanceType.JOINED)
@DiscriminatorColumn(name="CONTENT_TYPE", discriminatorType=javax.persistence.DiscriminatorType.INTEGER)
@DiscriminatorValue("4")In son class here is the annotation and query:
@Entity
@Table(name = "ISBN_BOOK")
@DiscriminatorValue("1000001")
@NamedQueries( {
@NamedQuery(name = "ISBN_BOOK.findViaISBN", query = "SELECT g FROM ISBNBook g WHERE g.ISBNnumber = :isbn")
})When I do the query, the result is:
Internal Exception: org.apache.derby.client.am.SqlException: Comparisons between 'INTEGER' and 'CHAR' are not supported.Error Code: -1
Call:SELECT t0.CONTENT_ID, t0.CONTENT_TYPE, t0.OBTAIN_DATE, t0.SEARCH_TIMES, t0.LAST_SEARCH_DATE, t1.CONTENT_ID, t1.BOOK_NAME, t1.AUTHOR, t1.ISBN_NUMBER, t1.CURRENT_LOCATION FROM CONTENT_MEDIA t0, ISBN_BOOK t1 WHERE ((t1.ISBN_NUMBER = CAST (? AS VARCHAR(32672) )) AND ((t1.CONTENT_ID = t0.CONTENT_ID) AND (t0.CONTENT_TYPE = '1000001')))
bind => [AAA]he problem is: t0.CONTENT_TYPE = '1000001'. I have set the column to Integer, why the JPA use the char?
Can anyone solve the problem for me?
I think now it is more readable.
(use code tags pls)

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hello everybody. i have a question about the non-static inner class. following is a block of codes:
i can declare and have a handle of a non-static inner class, like this : Inner0.HaveValue hv = inn.getHandle( 100 );
but why cannot i create an object of that non-static inner class by calling its constructor? like this : Inner0.HaveValue hv = Inner0.HaveValue( 100 );
is it true that "you can never CREATE an object of a non-static inner class( an object of Inner0.HaveValue ) without an object of the outer class( an object of Inner0 )"??
does the object "hv" in this program belong to the object of its outer class( that is : "inn" )? if "inn" is destroyed by the gc, can "hv" continue to exist?
thanks a lot. I am a foreigner and my english is not very pure. I hope that i have expressed my idea clearly.
// -------------- the codes -------------------
import java.util.*;
public class Inner0 {
// definition of an inner class HaveValue...
private class HaveValue {
private int itsVal;
public int getValue() {
return itsVal;
public HaveValue( int i ) {
itsVal = i;
// create an object of the inner class by calling this function ...
public HaveValue getHandle( int i ) {
return new HaveValue( i );
public static void main( String[] args ) {
Inner0 inn = new Inner0();
Inner0.HaveValue hv = inn.getHandle( 100 );
System.out.println( "i can create an inner class object." );
System.out.println( "i can also get its value : " + hv.getValue() );
return;
// -------------- end of the codes --------------

when you want to create an object of a non-static inner class, you have to have a reference of the enclosing class.
You can create an instance of the inner class as:
outer.inner oi = new outer().new inner();

Question about access non-public class from other package.

Hi, everyone!
Suppose class A and class B are in the same java file of package pkg1
-- A.java. So, A is a public class and B is a non-public class.
If I want to access class B from another class class C and class
C is in package pkg2. When compiling, an error occurs indicating
that class B is not visible to class C.
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Question about view/controller/nib class design

Assume you need to make an application with, let's say, 15 different views in total. There are two extreme design choices you can use to implement the app:
1) Every single view has its own view controller and a nib file. Thus you end up with 15 controller classes and 15 nib files (and possibly a bunch of view classes if any of your views needs to be somehow specialized).
2) You have only one controller which manages all the views, and one nib file from which they are loaded.
AFAIK Apple and many books recommend going purely with option #1. However, going with this often results in needless complexity, large amounts of classes (and nib files) to be managed and complicated class dependencies, especially if some of the views (and thus their controllers) interact with each other or share something (something which would be greatly simplified if all these related views were handled by one single controller class).
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Somehow I get the feeling that my question was slightly misunderstood.
I was not asking "which one of these two designs do you think is better, option #1 or option #2?" I already said in my original post that option #2 is bad design (unless your application consists of just one or two views). That's not the issue.
The issue is that from my own experience trying to adhere very strictly to the "every single view must have its own view controller and nib file" often results in needless complexity. Of course this is not always the case, but sometimes you end up having controller classes which perform very similar, if not even the exact same actions, resulting in code repetition. (An OO'ish solution to this problem would be to have a common base class for these view controllers where the common functionality has been grouped, but this often just adds to the overall complexity of the class hierarchy rather than alleviating it.)
As an example, let's assume that you have a set of help screens (for example one help screen for each major feature of the app) and a view where you can select which help view to show. Every one of these views has, for example, a button to immediately exit the help system. If you had one single controller class managing these views, this becomes simpler: The controller can switch between any of the views and the buttons of each view (most of them doing the same things) can call back actions on this controller (eg. to return to the help selection or to exit the help screen completely). These help screens don't necessarily have any functionality of their own, so it's questionable what do they would need view controllers of their own. These view controllers would basically be empty because there's nothing special for them to do.
View controllers might make it easy to use the navigation controller class, but the navigation controller is suitable mainly for utility apps but often not for things like games. (And if you need animated transitions between views, that can be implemented using the UIView animation features.)
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If I have interface Foo that extends interface Bar, I'm wondering if there's a way for Foo to add more documentation to one of Bar's methods.
For example, if I have:
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jverd wrote:
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I know I should normally start with posting the query but my question will take a little different direction, so here is the deal:
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Hi there
geo2 wrote:
We have an Apex application, there is a query on one of the pages that for certain users takes quite long, lets say 1min to 2 min, depending on how many records the query returns. The actual query varies depedning on some security settings and other parameters on the page - it's constructed by pl/sql function returning sql.To render a page, Apex does much some more stuff than just run the query. For instance, depending on the type of pagination you have enabled it needs to get the total number of rows to display "x to y of z" (or to display the message "more than nnn rows found"). Have you enabled debugging in Apex to be sure that most of the waiting time is spent on that query?
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myotherimage SI_StillImage;
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maybe in a plainer sentence will help??
so sorry for not understand it.The following is not necessarily accurate in every technical detail, but it's close enough to demonstrate the principles.
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Java Persistance: Question about query within inheritance class

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