Think\Controller:getDbError方法不存在！

FILE: D:\wwwroot\china-tongyuc_rhie4l\web\ThinkPHP\Library\Think\Controller.class.php 　LINE: 173

#0 D:\wwwroot\china-tongyuc_rhie4l\web\ThinkPHP\Library\Think\Controller.class.php(173): E('Think\\Controlle...')
#1 D:\wwwroot\china-tongyuc_rhie4l\web\App\Home\Controller\CategoryController.class.php(67): Think\Controller->__call('getDbError', Array)
#2 D:\wwwroot\china-tongyuc_rhie4l\web\App\Home\Controller\CategoryController.class.php(67): Home\Controller\CategoryController->getDbError()
#3 D:\wwwroot\china-tongyuc_rhie4l\web\App\Home\Controller\CategoryController.class.php(29): Home\Controller\CategoryController->_guestbook()
#4 [internal function]: Home\Controller\CategoryController->index()
#5 D:\wwwroot\china-tongyuc_rhie4l\web\ThinkPHP\Library\Think\App.class.php(164): ReflectionMethod->invoke(Object(Home\Controller\CategoryController))
#6 D:\wwwroot\china-tongyuc_rhie4l\web\ThinkPHP\Library\Think\App.class.php(202): Think\App::exec()
#7 D:\wwwroot\china-tongyuc_rhie4l\web\ThinkPHP\Library\Think\Think.class.php(123): Think\App::run()
#8 D:\wwwroot\china-tongyuc_rhie4l\web\ThinkPHP\ThinkPHP.php(98): Think\Think::start()
#9 D:\wwwroot\china-tongyuc_rhie4l\web\index.php(11): require('D:\\wwwroot\\chin...')
#10 {main}