【2018.06.19學習筆記】【linux高級知識 13.1-13.3】

13.1 設置更改root密碼

先啓動mysql：

[root@nginx ~]# /etc/init.d/mysqld start
Starting MySQL. SUCCESS! 
[root@nginx ~]# ps aux |grep mysql
root       1407  0.4  0.0 113308  1624 pts/0    S    20:27   0:00 /bin/sh /usr/local/mysql//bin/mysqld_safe --datadir=/data/mysql/ --pid-file=/data/mysql//nginx.pid
mysql      1515  5.5 24.1 1300824 451192 pts/0  Sl   20:27   0:00 /usr/local/mysql/bin/mysqld --basedir=/usr/local/mysql --datadir=/data/mysql --plugin-dir=/usr/local/mysql/lib/plugin --user=mysql --log-error=/data/mysql/nginx.err --pid-file=/data/mysql//nginx.pid
root       1539  0.0  0.0 112720   972 pts/0    R+   20:27   0:00 grep --color=auto mysql

登陸mysql：

mysql -uroot  //以用戶root登陸
[root@nginx ~]# mysql -uroot
-bash: mysql: 未找到命令

若是此時提示：mysql，無此命令，是由於沒有把/usr/local/mysql/bin/mysql 加入PATH環境變量中

能夠臨時加入：mysql就生效了

[root@nginx ~]# export PATH=$PATH:/usr/local/mysql/bin/
[root@nginx ~]# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.6.36 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>

要永久生效，就要在/etc/profile 下加入

[root@nginx ~]# vim /etc/profile
##省略內容
unset -f pathmunge
export PATH=$PATH:/usr/local/mysql/bin/mysql
[root@nginx ~]# source /etc/profile  //使配置生效

或者用別名：

alias mysql='/usr/local/mysql/bin/mysql'

指定用戶和密碼登陸：

[root@nginx ~]# mysql -uroot -p  //回車，而後輸入密碼便可登陸，無密碼直接按回車。
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.6.36 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>

若是root沒有密碼，能夠設置密碼：

[root@nginx ~]# mysqladmin -uroot password '7826078'  //在單引號內設置密碼，按回車
Warning: Using a password on the command line interface can be insecure.
[root@nginx ~]# mysql -uroot -p7826078  //登陸驗證
Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 7
Server version: 5.6.36 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>

修改密碼：

[root@nginx ~]# mysqladmin -uroot -p'7826078' password '961303'  //按回車修改生效
Warning: Using a password on the command line interface can be insecure.
[root@nginx ~]# mysql -uroot -p961303
Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 11
Server version: 5.6.36 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>

若是密碼忘記了，能夠重置密碼：

[root@nginx ~]# vim /etc/my.cnf  //在配置文件的[mysqld]下增長

# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.6/en/server-configuration-defaults.html
# *** DO NOT EDIT THIS FILE. It's a template which will be copied to the
# *** default location during install, and will be replaced if you
# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.6/en/server-configuration-defaults.html
# *** DO NOT EDIT THIS FILE. It's a template which will be copied to the
# *** default location during install, and will be replaced if you
# *** upgrade to a newer version of MySQL.

[mysqld]
skip-grant   //忽略受權
[root@nginx ~]# /etc/init.d/mysqld restart  //重啓一下mysql服務。
Shutting down MySQL.. SUCCESS! 
Starting MySQL. SUCCESS! 
[root@nginx ~]# mysql -uroot   //而後再登陸就不用密碼了
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.6.36 MySQL Community Server (GPL)

mysql> use mysql  //切換到mysql庫，修改mysql庫下的user表
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 password from user where user='root';  //查詢root用戶的密碼字段，密碼是加密顯示的，是password函數生成的
+-------------------------------------------+
| password                                  |
+-------------------------------------------+
| *3169EA1E35BFDB495D332C42C34EBB9E797543DD |
|                                           |
|                                           |
|                                           |
+-------------------------------------------+
4 rows in set (0.00 sec)

mysql> update user set password=password('7826078') where user='root'; //在user表裏更新root用戶的密碼
Query OK, 4 rows affected (0.01 sec)
Rows matched: 4  Changed: 4  Warnings: 0

[root@nginx ~]# vim /etc/my.cnf //在配置文件的[mysqld]下，刪除這行 skip grant
[root@nginx ~]# /etc/init.d/mysqld restart //重啓一下mysql服務。而後就能夠用新密碼登陸了
Shutting down MySQL.. SUCCESS! 
Starting MySQL. SUCCESS! 

[root@nginx ~]# mysql -uroot -p7826078  //用新密碼登陸成功
Warning: Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.6.36 MySQL Community Server (GPL)

13.2 鏈接mysql

鏈接本機的mysql: tcpip協議通訊

mysql -uroot -p密碼  //直接輸入用戶名和密碼，默認就是鏈接本機的mysql

鏈接遠程的mysql： tcpip協議通訊

mysql -uroot -p密碼 -h127.0.0.1 -P3306 //-h指定遠程ip，-P指定遠程端口

若是本機安裝了多個mysql，能夠指定socket鏈接mysql： socket協議通訊

mysql -uroot -p密碼 -S/tmp/mysql.sock //也是鏈接本機的mysql

在shell中經常使用的，鏈接mysql後，執行一些命令：

mysql -uroot -p密碼 -e "show databases"

13.3 mysql經常使用命令

查詢庫：

show databases;

切換到指定庫：

use mysql; //mysql是指定的庫名

查看錶：

show tables;

查看錶的字段：

desc 表名;

查看錶是怎麼建立的：

show creat table 表名\G; //G 縱向顯示

查看當前登陸用戶：

select user();

查看當前使用的庫：

select database();

建立庫：

creat databases db1; // db1爲庫名

建立表：

creat table 表名('字段1' 類型，'字段2' 類型);
craet table t1('id' int(4),'name' char(40)) ENGINE=InnoDB DEFAULT CHARSET=utf8;

查看數據庫版本：

select version();

查看狀態：

show status;

查看各參數：

show variables;

查看具體參數：

show variables like 'max_connect%';  //%是通配符

修改參數：

set global max_connect_errors=1000; //在內存中生效，要永久生效，該my.cnf文件

查看隊列：

show processlist; //查看進程信息，mysql在作什麼操做

查看完整隊列信息：

show full processlist; //完整的進程信息，什麼用戶鏈接、執行什麼操做、有無鎖表等。