code: private static void removeAll(Connection conn, ArrayList<String> usedTables) {
  	int len = usedTables.size();
  
  	for (int i = 0; i < len; i++) {
  
  	    String tableName = usedTables.get(i).toString();
  	    // print.out("remove:"+tableName);
  	    try {
  		removeTable(conn, tableName);
  	    }
  	    catch (Throwable t) {
  		ExceptionUtil.rethrowIfNecessary(t);
  	    }
  	}
      }
docs: remove all table inside the memory database
  
  @param conn