Index: org/exolab/castor/jdo/engine/SQLEngine.java
===================================================================
RCS file: /scm/castor/castor/src/main/org/exolab/castor/jdo/engine/SQLEngine.java,v
retrieving revision 1.26
diff -u -r1.26 SQLEngine.java
--- org/exolab/castor/jdo/engine/SQLEngine.java	29 Oct 2004 14:40:05 -0000	1.26
+++ org/exolab/castor/jdo/engine/SQLEngine.java	19 Feb 2005 16:00:47 -0000
@@ -116,7 +116,7 @@
     private ColumnInfo[]         _ids;
 
     private SQLEngine           _extends;
-
+    
     private QueryExpression     _sqlFinder;
 
     private PersistenceFactory  _factory;
@@ -1373,6 +1373,54 @@
                               baseDesc.getTableName(), baseDesc.getIdentityColumnNames());
             curDesc = baseDesc;
         }
+        
+        curDesc = clsDesc;
+        List classDescriptorsToAdd = new LinkedList();
+        JDOClassDescriptor classDescriptor = null;
+        addExtendingClassDescriptors(classDescriptorsToAdd, curDesc.getExtendedBy());
+        
+        if (classDescriptorsToAdd.size() > 0) {
+        	for (Iterator iter = classDescriptorsToAdd.iterator(); iter.hasNext(); ) {
+        		classDescriptor = (JDOClassDescriptor) iter.next();
+        		_log.debug ("Adding outer left join for " + classDescriptor.getJavaClass().getName() + 
+        				" on table " + classDescriptor.getTableName());
+                expr.addOuterJoin( _mapTo, 
+                		curDesc.getIdentityColumnNames(), 
+                		classDescriptor.getTableName(), 
+                		classDescriptor.getIdentityColumnNames());
+                find.addOuterJoin( _mapTo, 
+                		curDesc.getIdentityColumnNames(), 
+                		classDescriptor.getTableName(), 
+                		classDescriptor.getIdentityColumnNames());
+
+//                String[] identityColumnNames = classDescriptor.getIdentityColumnNames();
+//                for (int i = 0; i < identityColumnNames.length; i++) {
+//                    expr.addColumn (classDescriptor.getTableName(), identityColumnNames[i]);
+//                    find.addColumn (classDescriptor.getTableName(), identityColumnNames[i]);
+//                }
+                
+//                Persistence persistenceEngine;
+//				try {
+//					persistenceEngine = _factory.getPersistence (classDescriptor);
+//				} catch (MappingException e) {
+//					throw new QueryException ("Problem obtaining persistence engine for ClassDescriptor " + classDescriptor.getJavaClass().getName(), e);
+//				}
+//				
+//                SQLEngine.FieldInfo[] fieldInfos = (SQLEngine.FieldInfo[]) persistenceEngine.getInfo();
+//                for (int i = 0; i < fieldInfos.length; i++) {
+//                	SQLEngine.ColumnInfo[] columnInfos = fieldInfos[i].columns;
+//                    for ( int j = 0; j < columnInfos.length; j++ ) {
+//                        expr.addColumn (classDescriptor.getTableName(), fieldInfos[i].columns[j].name);
+//                        find.addColumn (classDescriptor.getTableName(), fieldInfos[i].columns[j].name);
+//                    }
+//                    expr.addTable(classDescriptor.getTableName());
+//                    find.addTable(classDescriptor.getTableName());
+//                }
+        	}
+        }
+
+        // TODO [WG]: add code to add left outer joins
+
         for ( int i=0; i<_ids.length; i++ ) {
             find.addColumn( _mapTo, idnames[i] );
         }
@@ -1417,6 +1465,16 @@
             _log.debug( Messages.format( "jdo.loading", _type, _sqlLoad ) );
         }
         
+    }
+    
+    private void addExtendingClassDescriptors (Collection classDescriptorsToAdd, Collection extendingClassDescriptors) {
+    	JDOClassDescriptor classDescriptor = null; 
+        for (Iterator iter = extendingClassDescriptors.iterator(); iter.hasNext(); ) {
+        	classDescriptor = (JDOClassDescriptor) iter.next(); 
+        	classDescriptorsToAdd.add (classDescriptor);
+        	addExtendingClassDescriptors(classDescriptorsToAdd, classDescriptor.getExtendedBy());
+        }
+    	
     }
 
 
Index: org/exolab/castor/mapping/ClassDescriptor.java
===================================================================
RCS file: /scm/castor/castor/src/main/org/exolab/castor/mapping/ClassDescriptor.java,v
retrieving revision 1.1.1.1
diff -u -r1.1.1.1 ClassDescriptor.java
--- org/exolab/castor/mapping/ClassDescriptor.java	3 Mar 2003 07:08:26 -0000	1.1.1.1
+++ org/exolab/castor/mapping/ClassDescriptor.java	19 Feb 2005 16:00:47 -0000
@@ -46,6 +46,8 @@
 
 package org.exolab.castor.mapping;
 
+import java.util.Collection;
+
 
 /**
  * Describes the properties of a class and its fields. Implementations
@@ -65,7 +67,6 @@
      * @return The Java class
      */
     public Class getJavaClass();
-
 
     /**
      * Returns a list of fields represented by this descriptor.
Index: org/exolab/castor/mapping/loader/ClassDescriptorImpl.java
===================================================================
RCS file: /scm/castor/castor/src/main/org/exolab/castor/mapping/loader/ClassDescriptorImpl.java,v
retrieving revision 1.1.1.1
diff -u -r1.1.1.1 ClassDescriptorImpl.java
--- org/exolab/castor/mapping/loader/ClassDescriptorImpl.java	3 Mar 2003 07:08:29 -0000	1.1.1.1
+++ org/exolab/castor/mapping/loader/ClassDescriptorImpl.java	19 Feb 2005 16:00:48 -0000
@@ -47,6 +47,12 @@
 package org.exolab.castor.mapping.loader;
 
 
+import java.util.Collection;
+import java.util.Collections;
+import java.util.LinkedList;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.exolab.castor.mapping.ValidityException;
 import org.exolab.castor.mapping.ClassDescriptor;
 import org.exolab.castor.mapping.FieldDescriptor;
@@ -67,7 +73,7 @@
 public class ClassDescriptorImpl
     implements ClassDescriptor
 {
-
+	private static final Log _log = LogFactory.getLog (ClassDescriptorImpl.class);
 
     private ClassMapping         _map;
     /**
@@ -86,6 +92,12 @@
      * or null if this is a top-level class.
      */
     private final ClassDescriptor     _extends;
+    
+    /**
+     * A collection of class descriptors that extend this class, or 
+     * an empty collection if this is a leaf class.
+     */
+    private final Collection	  _extendedBy = new LinkedList();
 
 
     private final ClassDescriptor     _depends;
@@ -167,6 +179,13 @@
                 throw new MappingException( "mapping.classDoesNotExtend",
                                             _javaClass.getName(), extend.getJavaClass().getName() );
             _extends = extend;
+            
+            _log.debug (_extends.getClass().getName());
+            if ( _extends.getClass().getName().equals("org.exolab.castor.jdo.engine.JDOClassDescriptor") &&
+            	this.getClass().getName().equals ("org.exolab.castor.jdo.engine.JDOClassDescriptor")) {
+            	((ClassDescriptorImpl) _extends).addExtendedBy (this);
+            }
+            
             if ( _extends instanceof ClassDescriptorImpl )
                 _identities = ( identities == null ? ((ClassDescriptorImpl)_extends).getIdentities() : identities );
             else
@@ -233,6 +252,21 @@
     public ClassDescriptor getExtends()
     {
         return _extends;
+    }
+    
+    /**
+     * Returns a collection of class descriptors that extend this class descriptor.
+     * @return A collection of class descriptors.
+     */
+    public Collection getExtendedBy() 
+    {
+    	return _extendedBy;
+    }
+    
+    public void addExtendedBy (ClassDescriptor classDesc) 
+    {
+    	_log.debug ("Adding ClassDescriptor of type " + classDesc.getClass().getName());
+    	_extendedBy.add (classDesc);
     }
 
     public ClassDescriptor getDepends() {