SQLSTATE[HY000] [2002] No route to host

FILE: /www/wwwroot/www.mseatech.com/ThinkPHP/Library/Think/Db/Driver.class.php 　LINE: 199

#0 /www/wwwroot/www.mseatech.com/ThinkPHP/Library/Think/Db/Driver.class.php(199): E('SQLSTATE[HY000]...')
#1 /www/wwwroot/www.mseatech.com/ThinkPHP/Library/Think/Db/Driver.class.php(116): Think\Db\Driver->connect()
#2 /www/wwwroot/www.mseatech.com/ThinkPHP/Library/Think/Db/Driver/Mysql.class.php(26): Think\Db\Driver->initConnect(true)
#3 /www/wwwroot/www.mseatech.com/ThinkPHP/Library/Think/Model.class.php(190): Think\Db\Driver\Mysql->getFields('zh_contact')
#4 /www/wwwroot/www.mseatech.com/ThinkPHP/Library/Think/Model.class.php(178): Think\Model->flush()
#5 /www/wwwroot/www.mseatech.com/ThinkPHP/Library/Think/Model.class.php(149): Think\Model->_checkTableInfo()
#6 /www/wwwroot/www.mseatech.com/ThinkPHP/Library/Think/Model.class.php(97): Think\Model->db(0, '', true)
#7 /www/wwwroot/www.mseatech.com/ThinkPHP/Common/functions.php(623): Think\Model->__construct('contact', '', '')
#8 /www/wwwroot/www.mseatech.com/Application/Home/Controller/WssbController.class.php(15): M('contact')
#9 [internal function]: Home\Controller\WssbController->wssb()
#10 /www/wwwroot/www.mseatech.com/ThinkPHP/Library/Think/App.class.php(201): ReflectionMethod->invoke(Object(Home\Controller\WssbController))
#11 /www/wwwroot/www.mseatech.com/ThinkPHP/Library/Think/App.class.php(133): Think\App::invokeAction(Object(Home\Controller\WssbController), 'wssb')
#12 /www/wwwroot/www.mseatech.com/ThinkPHP/Library/Think/App.class.php(34): Think\App::exec()
#13 /www/wwwroot/www.mseatech.com/ThinkPHP/Library/Think/Think.class.php(120): Think\App::run()
#14 /www/wwwroot/www.mseatech.com/ThinkPHP/ThinkPHP.php(97): Think\Think::start()
#15 /www/wwwroot/www.mseatech.com/index.php(33): require('/www/wwwroot/ww...')
#16 {main}