protected String createEntityExistsSQL() 
{
      return null;
}

 protected boolean entityExists(Object pk) throws CreateException 
{
      return false;
}

 public Object execute(Method m,
    Object[] args,
    EntityEnterpriseContext ctx) throws CreateException 
{
      // primary key to return
      Object pk = null;
      if(!createAllowed)
      {
         throw new CreateException("Creation is not allowed because a " +
            "primary key field is read only.");
      }
      // the key is generated by the database
      insertEntity(ctx);
      pk = entity.extractPrimaryKeyFromInstance(ctx);
      log.debug("Created: pk="+pk);
      return pk;
}

 protected List getInsertFields() 
{
      List fields = entity.getFields();
      List insertFields = new ArrayList(fields.size());
      for( Iterator iter = fields.iterator(); iter.hasNext(); )
      {
         JDBCFieldBridge field = (JDBCFieldBridge)iter.next();
         if( !field.isReadOnly() && !field.isPrimaryKeyMember() )
         {
            insertFields.add(field);
         } 
      }
      return insertFields;
}

The method adds to insert fields only non-primary key fields

 public  void init(JDBCStoreManager manager) 
{
      this.manager = manager;
      entity = manager.getEntityBridge();
      // Create the Log
      log = Logger.getLogger( this.getClass().getName()
         + "." + manager.getMetaData().getName());
      // set create allowed
      createAllowed = true;
      List fields = entity.getFields();
      for( Iterator iter = fields.iterator(); iter.hasNext(); )
      {
         JDBCFieldBridge field = (JDBCFieldBridge)iter.next();
         if( field.isPrimaryKeyMember() && field.isReadOnly() )
         {
            createAllowed = false;
            break;
         }
      }
      if(createAllowed)
      {
         insertFields = getInsertFields();
         insertEntitySQL = createInsertEntitySQL();
         log.debug("Insert Entity SQL: " + insertEntitySQL);
      }
      else
      {
         log.debug("Create will not be allowed.");
      }
}

The method differs only in that, it has no entityExistsSQL

 protected  void insertEntity(EntityEnterpriseContext ctx) throws CreateException 
{
      Connection con = null;
      PreparedStatement ps = null;
      int rowsAffected  = 0;
      try
      {
         // get the connection
         DataSource dataSource = entity.getDataSource();
         con = dataSource.getConnection();
         // create the statement
         log.debug("Executing SQL: " + insertEntitySQL);
         ps = con.prepareStatement(insertEntitySQL,
                 PreparedStatement.RETURN_GENERATED_KEYS);
         // set the parameters
         int index = 1;
         for( Iterator iter = insertFields.iterator(); iter.hasNext(); )
         {
            JDBCFieldBridge field = (JDBCFieldBridge)iter.next();
            index = field.setInstanceParameters(ps, index, ctx);
         }
         // execute statement
         rowsAffected = ps.executeUpdate();
         // check results
         if(rowsAffected != 1)
         {
            throw new CreateException("Insertion failed. Expected one " +
               "affected row: rowsAffected=" + rowsAffected +
               "id=" + ctx.getId());
         }
         log.debug("Rows affected = " + rowsAffected);
         // fetch generated keys
         ResultSet rs = ps.getGeneratedKeys();
         Object pk = null;
         if( rs.next() ) pk = rs.getObject( 1 );
         if( pk == null )
         {
            throw new Exception( "Primary key isn't generated." );
         }
         // write pk fields to the context
         for( Iterator iter = entity.getPrimaryKeyFields().iterator();
            iter.hasNext(); )
         {
            JDBCCMPFieldBridge cmpField = (JDBCCMPFieldBridge) iter.next();
            cmpField.setInstanceValue( ctx, pk );
            break;
         }
      }
      catch( CreateException ce )
      {
         throw ce;
      }
      catch(Exception e)
      {
         log.error("Could not create entity", e);
         throw new CreateException("Could not create entity:" + e);
      } finally {
         JDBCUtil.safeClose(ps);
         JDBCUtil.safeClose(con);
      }
      // Mark the inserted fields as clean.
      for( Iterator iter = insertFields.iterator(); iter.hasNext(); )
      {
         JDBCFieldBridge field = (JDBCFieldBridge)iter.next();
         field.setClean(ctx);
      }
}