PHP Framework Db Error

Error messages:
  • [Type] 无法连接到数据库服务器
 
Program messages:
  • [Line: 0013]index.php(class_core::_get_instance)
  • [Line: 0029]class/core.php(class_core->__construct)
  • [Line: 0056]class/core.php(class_core->_dispatch)
  • [Line: 0445]class/core.php(school->view_action)
  • [Line: 0312]application/control/school.php(school->_zdcount)
  • [Line: 0140]application/control/school.php(db::isobject)
  • [Line: 0710]class/core.php(db::_object)
  • [Line: 0740]class/core.php(db_mysql->connect)
  • [Line: 0550]class/core.php(db_mysql->_dbconnect)