docs: public void execute() throws BuildException
      {
          if ((_commands == null) || (_commands.length() == 0))
          {
              return;
          }
  
          DBHandling handling = createDBHandling();
  
          try
          {
              if ((_workDir != null) && (_workDir.length() > 0))
              {
                  handling.setWorkDir(_workDir);
                  System.setProperty("user.dir", _workDir);
              }
              for (Iterator it = _fileSets.iterator(); it.hasNext();)
              {
                  addIncludes(handling, (FileSet)it.next());
              }
  
              if ((_propertiesFile != null) && (_propertiesFile.length() > 0))
              {
                  System.setProperty("OJB.properties", _propertiesFile);
              }
  
              ConnectionRepository connRep = MetadataManager.getInstance().connectionRepository();
              PBKey                pbKey   = null;
  
              if ((_jcdAlias == null) || (_jcdAlias.length() == 0))
              {
                  pbKey = PersistenceBrokerFactory.getDefaultKey();
              }
              else
              {
                  pbKey = connRep.getStandardPBKeyForJcdAlias(_jcdAlias);
                  if (pbKey == null)
                  {
                      throw new BuildException("Undefined jcdAlias "+_jcdAlias);
                  }
              }
              handling.setConnection(connRep.getDescriptor(pbKey));
  
              String command;
  
              for (StringTokenizer tokenizer = new StringTokenizer(_commands, ","); tokenizer.hasMoreTokens();)
              {
                  command = tokenizer.nextToken().toLowerCase().trim();
                  if (COMMAND_CREATE.equals(command))
                  {
                      handling.createDB();
                  }
                  else if (COMMAND_INIT.equals(command))
                  {
                      handling.initDB();
                  }
                  else
                  {
                      throw new BuildException("Unknown command "+command);
                  }
              }
          }
          catch (Exception ex)
          {
              throw new BuildException(ex);
          }
      }