MySQL错误:Can‘t connect to MySQL server on localhost解决办法(分多种情况)

mysql -uroot -p
mysql> show databases;
mysql> use mysql;
mysql> select host, user from user;

  mysql> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%'WITH GRANT OPTION;     #任何远程主机都可以访问数据库  
  mysql> FLUSH PRIVILEGES;    #需要输入次命令使修改生效  
  mysql> EXIT    #退出 

  mysql> use mysql;  
  mysql> update user set host = '%' where user = 'root';  
  mysql> select host, user from user;