SQLSTATE[HY000] [2002] Connection refused

FILE: /www/wwwroot/www.njgcsc.com/ThinkPHP/Library/Think/Db/Driver.class.php 　LINE: 109

#0 /www/wwwroot/www.njgcsc.com/ThinkPHP/Library/Think/Db/Driver.class.php(109): E('SQLSTATE[HY000]...')
#1 /www/wwwroot/www.njgcsc.com/ThinkPHP/Library/Think/Db/Driver.class.php(1064): Think\Db\Driver->connect()
#2 /www/wwwroot/www.njgcsc.com/ThinkPHP/Library/Think/Db/Driver/Mysql.class.php(47): Think\Db\Driver->initConnect(true)
#3 /www/wwwroot/www.njgcsc.com/ThinkPHP/Library/Think/Model.class.php(134): Think\Db\Driver\Mysql->getFields('blog_site')
#4 /www/wwwroot/www.njgcsc.com/ThinkPHP/Library/Think/Model.class.php(122): Think\Model->flush()
#5 /www/wwwroot/www.njgcsc.com/ThinkPHP/Library/Think/Model.class.php(1434): Think\Model->_checkTableInfo()
#6 /www/wwwroot/www.njgcsc.com/ThinkPHP/Library/Think/Model.class.php(97): Think\Model->db(0, '', true)
#7 /www/wwwroot/www.njgcsc.com/ThinkPHP/Common/functions.php(621): Think\Model->__construct('site', '', '')
#8 /www/wwwroot/www.njgcsc.com/Application/Home/Controller/BaseController.class.php(14): M('site')
#9 /www/wwwroot/www.njgcsc.com/ThinkPHP/Library/Think/Controller.class.php(41): Home\Controller\BaseController->_initialize()
#10 /www/wwwroot/www.njgcsc.com/ThinkPHP/Common/functions.php(681): Think\Controller->__construct()
#11 /www/wwwroot/www.njgcsc.com/ThinkPHP/Library/Think/App.class.php(89): controller('Index', '')
#12 /www/wwwroot/www.njgcsc.com/ThinkPHP/Library/Think/App.class.php(202): Think\App::exec()
#13 /www/wwwroot/www.njgcsc.com/ThinkPHP/Library/Think/Think.class.php(120): Think\App::run()
#14 /www/wwwroot/www.njgcsc.com/ThinkPHP/ThinkPHP.php(97): Think\Think::start()
#15 /www/wwwroot/www.njgcsc.com/index.php(28): require('/www/wwwroot/ww...')
#16 {main}