Hello again,
in fact we already use a table with a field for each table. This works quite
good. Thanks for the idea to cache it via a static field.
There is one thing to consider using this approach. If someone inserts data
into the table without using our beans, we end up with duplicate keys.
That's why we wanted the INFORMIX Server to handle this.
Thanks a lot for your help.
Best Regards,
Albert Brotzer
----- Original Message -----
From: Guillaume Rousse <[EMAIL PROTECTED]>
To: Albert Brotzer <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Sent: Thursday, March 30, 2000 11:13 AM
Subject: Re: server generated primary key
Don't know Informix, but i imagine it has you can also alter manually your
sequence generator.
So, let your Bean class set the id itself, using a static int property, and
have this property being sync to the sequence generator regulary. Here's the
code i used for postreSQL :
/**
* Gets the next account ID.
*/
private int getNewId() throws Exception {
if (verboseMode)
System.out.println("getNewAccountId(); lastKey: " + lastKey + " maxKey:
" + maxKey);
if (lastKey >= maxKey) {
// Go to database and set new values for lastKey and maxKey
if (verboseMode)
System.out.println("lastKey >= maxKey: getting new range of
accountIds");
Connection con=null;
PreparedStatement ps=null;
try {
con = dataSource.getConnection();
ps = con.prepareStatement("select setval('taxon_id_seq',
nextval('taxon_id_seq')+?);");
ps.setInt(1, keyRange-1);
ResultSet rs = ps.executeQuery();
if (rs==null) System.out.println("null");
if ((rs != null) && (rs.next())) {
maxKey = rs.getInt(1);
lastKey = maxKey - keyRange;
} else {
throw new CreateException ("ejbCreate: sequence failed to return a
value");
}
}
catch (Exception ex) {
throw new RemoteException (ex.getMessage());
}
finally {
try { ps.close();
con.close();
} catch (SQLException ex) {};
}
}
return ++lastKey;
}
If you can't use sequence generator, you can also use a table with a field
for
each of your EJB, and increment it manually.
Hope this helps
Le jeu, 30 mar 2000, vous avez �crit :
> Sorry, I accidentally sent this question to jonas-team instead of
> jonas-users.
>
> Here is my question:
>
> I'm using INFORMIX-OnLine with Jonas and want to make use of primary key
> values for my CMP-Beans generated by the INFORMIX-Server. This can be done
> with a SERIAL column in INFORMIX. I already know that there is no ANSI SQL
> way to do this, but as I just use INFORMIX I don't care much about
> portability in this respect. I already tried to do the following:
>
> - in the method ejbCreate() I set the primary key field (an Integer) to 0.
> This tells INFORMIX to generate a value that is unique in the table an can
> be used as a primary key for the table. This works fine so far, but I need
> to know which number the server generated for the row just inserted.
>
> - in the method ejbPostCreate() I execute the following code to get the
> primary-key value:
>
> try {
> conn = ... (utility to get a Connection)
> stmt = conn.createStatement();
> ResultSet res = stmt.executeQuery( "select
DBINFO( 'sqlca.sqlerrd1' )
> from " + Dt10001EB.TABLENAME );
> if( res.next() == false ) {
> throw new CreateException( "Can't determine primary key" );
> }
> int resId = res.getInt( 1 );
> id = new Integer( resId );
> Dt10001EBPK pk = (Dt10001EBPK)entityContext.getPrimaryKey();
> pk.id = id;
> System.out.println( "====> serial = " + resId );
> }
> catch( SQLException ex ) {
> throw new CreateException( ex.toString() );
> }
> catch( javax.naming.NamingException ex2 ) {
> throw new CreateException( ex2.toString() );
> }
> finally {
> try {
> if( stmt != null )
> stmt.close();
> if( conn != null )
> conn.close();
> }
> catch( SQLException ex3 ) {
> }
> }
>
> This code works quite well. But when I try to access fields from this bean
> within the same transaction I notice that the bean is loaded from the
> database again. This does not happen, when i create a bean with a primary
> key != 0. That's why I fear, that Jonas caches the primary key 0 before
> ejbPostCreate() is called and wonder if this solution would work in all
> circumstances or if I would end up with inconsistent EntityBeans in my
> container.
>
> Can someone please clear this up? Is there an easier way to use INFORMIX
> SERIALS?
>
> Best Regards,
> Albert
--
Guillaume Rousse
Iremia - Universit� de la R�union
15 avenue Ren� Cassin, BP 7151
97715 Saint Denis, messagerie cedex 9
Tel:0262938330 Fax:0262938260 ICQ:10756815
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