Unknown MySQL server host 'hdm373779472.my3w.com' (1)

FILE: /usr/home/hyu4054950001/htdocs/ThinkPHP/Library/Think/Db/Driver/Mysql.class.php 　LINE: 55

#0 /usr/home/hyu4054950001/htdocs/ThinkPHP/Library/Think/Db/Driver/Mysql.class.php(55): E('Unknown MySQL s...')
#1 /usr/home/hyu4054950001/htdocs/ThinkPHP/Library/Think/Db.class.php(166): Think\Db\Driver\Mysql->connect()
#2 /usr/home/hyu4054950001/htdocs/ThinkPHP/Library/Think/Db/Driver/Mysql.class.php(92): Think\Db->initConnect(false)
#3 /usr/home/hyu4054950001/htdocs/ThinkPHP/Library/Think/Db/Driver/Mysql.class.php(211): Think\Db\Driver\Mysql->query('SHOW COLUMNS FR...')
#4 /usr/home/hyu4054950001/htdocs/ThinkPHP/Library/Think/Model.class.php(130): Think\Db\Driver\Mysql->getFields('dzyh_category')
#5 /usr/home/hyu4054950001/htdocs/ThinkPHP/Library/Think/Model.class.php(118): Think\Model->flush()
#6 /usr/home/hyu4054950001/htdocs/ThinkPHP/Library/Think/Model.class.php(1298): Think\Model->_checkTableInfo()
#7 /usr/home/hyu4054950001/htdocs/ThinkPHP/Library/Think/Model.class.php(95): Think\Model->db(0, '', true)
#8 /usr/home/hyu4054950001/htdocs/Application/Common/Controller/HomeController.class.php(26): Think\Model->__construct()
#9 /usr/home/hyu4054950001/htdocs/ThinkPHP/Common/functions.php(613): Common\Controller\HomeController->__construct()
#10 /usr/home/hyu4054950001/htdocs/ThinkPHP/Library/Think/App.class.php(80): controller('Cases', '')
#11 /usr/home/hyu4054950001/htdocs/ThinkPHP/Library/Think/App.class.php(193): Think\App::exec()
#12 /usr/home/hyu4054950001/htdocs/ThinkPHP/Library/Think/Think.class.php(120): Think\App::run()
#13 /usr/home/hyu4054950001/htdocs/ThinkPHP/ThinkPHP.php(96): Think\Think::start()
#14 /usr/home/hyu4054950001/htdocs/index.php(30): require('/usr/home/hyu40...')
#15 {main}