code: private void updateDatabase() {
          if (getMainConfig().getInt("Database.dbVersion") == 0) {
              alertOldDbVersion(0, 1);
              //We first check if we have the DB version in the database. If we do, we have a old layout in our hands
              String value = getStorageHandler().getStorageEngine().getConfigEntry("dbVersion");
              if (value != null) {
                  //We have a old database, do the whole conversion
                  try {
                      new OldFormatConverter().run();
                      getMainConfig().setValue("Database.dbVersion", 1);
                      sendConsoleMessage(Level.INFO, "Updated to Revision 1!");
  
                  } catch (SQLException e) {
                      e.printStackTrace();
                  } catch (IOException e) {
                      e.printStackTrace();
                  } catch (ParseException e) {
                      e.printStackTrace();
                  }
              } else {
                  getMainConfig().setValue("Database.dbVersion", 1);
                  sendConsoleMessage(Level.INFO, "Updated to Revision 1!");
              }
          } else if (getMainConfig().getInt("Database.dbVersion") == -1) {
              alertOldDbVersion(-1,1);
              try {
                      new OldFormatConverter().step2();
                      getMainConfig().setValue("Database.dbVersion", 1);
                      sendConsoleMessage(Level.INFO, "Updated to Revision 1!");
  
                  } catch (SQLException e) {
                      e.printStackTrace();
                  } catch (IOException e) {
                      e.printStackTrace();
                  } catch (ParseException e) {
                      e.printStackTrace();
                  }
          }
      }
docs: Run a database update.