问题如下：
Failed to Connect to MySQL at 127.0.0.1:3306 with user root Access denied for user 'root'@'localhost'
我的问题是terminal中可以使用管理员账号登录mysql，但是在使用workbench时，链接就会出现上面的问题
问题如图
网上看了许多方法，试验了几个，发现新建一个用户解决办法最简单。
创建用户
格式：create user 'userName'@'localhost' identified by 'passward';
mysql> create user 'dfzxk'@'localhost' identified by '123456';
Query OK, 0 rows affected (0.00 sec)
给user上帝权限
mysql> grant all on *.* to dfzxk@"%" identified by "123456";
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql授权东西太多，不多说了
查看用户权限
mysql> show grants for dfzxk;
+--------------------------------------------+
| Grants for dfzxk@% |
+--------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'dfzxk'@'%' |
+--------------------------------------------+
1 row in set (0.00 sec)
再次使用workbench，已经链接成功了。
遇到的坑
mysql> create user 'dflx'@'localhost' identified by '123456';
ERROR 1396 (HY000): Operation CREATE USER failed for 'dflx'@'localhost'
据说是已经建立了这个用户，我Ubuntu的xwindows桌面崩溃过一次，因为\目录太小的原因，我准备增大根目录的容量，把\home移动5g给它，可是现在卡在了这里。
sql语句查看一下
mysql> show database;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'database' at line 1
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| mysql_shiyan |
| performance_schema |
| sys |
| test |
+--------------------+
6 rows in set (0.00 sec)
mysql> use mysql;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
mysql> select host,user from mysql.user;
+-----------+------------------+
| host | user |
+-----------+------------------+
| % | dfzxk |
| localhost | debian-sys-maint |
| localhost | dflx |
| localhost | dfzxk |
| localhost | mysql.session |
| localhost | mysql.sys |
| localhost | root |
+-----------+------------------+
7 rows in set (0.00 sec)
mysql> show grants for dflx;
ERROR 1141 (42000): There is no such grant defined for user 'dflx' on host '%'
果然我的dflx用户还在，我workbench链接了一下，成功了，但是说没有授权，可是我workbench进行了，增加，查询，好像没有问题啊（嘻嘻）
show databases;
use test;
show tables;
select * from user;
insert into user values('dfzxk','123456');
结果如下：
学的是SQL server，对于mysql这些有些不太熟悉，但是sql语法大体通用的。
修改root密码如下
上面说的
mysql> set password for root@localhost=password("123456");
Query OK, 0 rows affected, 2 warnings (0.02 sec)
mysql> select host,user,grant_priv from user;
+-----------+------------------+------------+
| host | user | grant_priv |
+-----------+------------------+------------+
| localhost | root | Y |
| localhost | mysql.session | N |
| localhost | mysql.sys | N |
| localhost | debian-sys-maint | Y |
| localhost | dflx | N |
| % | dflx | N |
+-----------+------------------+------------+
6 rows in set (0.04 sec)
mysql> select host,user,grant_priv,alter_priv,password_expired from user;
+-----------+------------------+------------+------------+------------------+
| host | user | grant_priv | alter_priv | password_expired |
+-----------+------------------+------------+------------+------------------+
| localhost | root | Y | Y | N |
| localhost | mysql.session | N | N | N |
| localhost | mysql.sys | N | N | N |
| localhost | debian-sys-maint | Y | Y | N |
| localhost | dflx | N | N | N |
| % | dflx | N | Y | N |
+-----------+------------------+------------+------------+------------------+
6 rows in set (0.00 sec)
mysql> select host,user,grant_priv,pass_last_change from user;
ERROR 1054 (42S22): Unknown column 'pass_last_change' in 'field list'
mysql> select host,user,grant_priv,pass_last_changed from user;
ERROR 1054 (42S22): Unknown column 'pass_last_changed' in 'field list'
mysql> select host,user,grant_priv,password_last_changed from user;
+-----------+------------------+------------+-----------------------+
| host | user | grant_priv | password_last_changed |
+-----------+------------------+------------+-----------------------+
| localhost | root | Y | 2018-07-01 17:10:59 |
| localhost | mysql.session | N | 2018-07-01 17:11:00 |
| localhost | mysql.sys | N | 2018-07-01 17:11:00 |
| localhost | debian-sys-maint | Y | 2018-07-01 17:11:01 |
| localhost | dflx | N | 2018-07-07 21:10:00 |
| % | dflx | N | 2018-07-07 21:24:55 |
+-----------+------------------+------------+-----------------------+
6 rows in set (0.00 sec)
mysql> set password for root@localhost=password("123456");
Query OK, 0 rows affected, 2 warnings (0.02 sec)
我Ubuntu的xwindows桌面崩溃过一次，因为\目录太小的原因，
当时安装系统时看网上教程一大推说，给根目录10g就行了，swap是内存二倍，
感觉这个建议很坑啊，网上一大推抱怨这个\目录10g的，可是给根目录增加容量
不容易啊！我准备增大根目录的容量，把\home移动5g给它，可是现在卡在了这里。
我整理了半天垃圾，现在还是这个情况,如果\目录剩余太小了，会发生很可怕的问题。
dfzxk@satan-master:~$ df -h
文件系统 容量 已用 可用 已用% 挂载点
udev 1.9G 0 1.9G 0% /dev
tmpfs 382M 41M 342M 11% /run
/dev/sda8 9.4G 7.0G 2.0G 79% /
/dev/sda9 47G 13G 32G 30% /usr
tmpfs 1.9G 65M 1.8G 4% /dev/shm
tmpfs 5.0M 4.0K 5.0M 1% /run/lock
tmpfs 1.9G 0 1.9G 0% /sys/fs/cgroup
/dev/sda10 22G 1.4G 19G 7% /home
/dev/sda1 196M 29M 168M 15% /boot/efi
tmpfs 382M 40K 382M 1% /run/user/1003
参考文章:
[mysql Access denied for user root@localhost错误解决方法总结](http://www.111cn.net/database/mysql/44142.htm)
[MYSQL登录错误：mysqladmin: connect to server at 'localhost' failed](http://blog.csdn.net/j3smile/article/details/14134879)
[Failed to connect to mysql at 127.0.0.1:3306 with user root access denied for user 'root'@'localhost'(using password:YES)](https://stackoverflow.com/questions/25777943/failed-to-connect-to-mysql-at-127-0-0-13306-with-user-root-access-denied-for-us)
[
解决database - Failed to connect to mysql at 127.0.0.1:3306 with user root access denied for user 'root'@'localhost'](http://www.111cn.net/database/mysql/44142.htm)
[MySQL添加用户、删除用户与授权](http://www.cnblogs.com/wanghetao/p/3806888.html)
教您如何查看MySQL用户权限 [教您如何查看MySQL用户权限](http://www.cnblogs.com/cnteam/articles/4272460.html)
windows下出现问题
Microsoft Windows [版本 10.0.16299.125]
(c) 2017 Microsoft Corporation。保留所有权利。
C:\WINDOWS\system32>cd C:\mysql-5.7.20-winx64\mysql-5.7.20-winx64\bin
C:\mysql-5.7.20-winx64\mysql-5.7.20-winx64\bin>mysqld.exe
C:\mysql-5.7.20-winx64\mysql-5.7.20-winx64\bin>mysql
ERROR 1045 (28000): Access denied for user 'ODBC'@'localhost' (using password: NO)
C:\mysql-5.7.20-winx64\mysql-5.7.20-winx64\bin>mysql -u -p
ERROR 1045 (28000): Access denied for user '-p'@'localhost' (using password: NO)
C:\mysql-5.7.20-winx64\mysql-5.7.20-winx64\bin>mysql -u root
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.7.20 MySQL Community Server (GPL)
Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>
