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
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