Mysql 基本用法

MYSQL语句

一. SQL语句的三种类型：
DDL ： 数据定义语言
DML ： 数据操纵语言
DCL ： 数据控制语言

二. Maysql语言的操作类型

类型	对应操纵
DDL	CREATE :创建 ,DROP：删除，ALTER：修改
DML	INSERT：向表中插入数据，DELETE：删除表中数据，UPDATE：更新表中数据，SELECT：查询表中数据
DCL	GRANT：授权，REEVOKE：移除授权

三 . mysql的安装方式：

1. 源代码：编译安装
2. 二进制格式的程序包：展开至特定路径，并经过简单配置后即可使用
3. 程序包管理器的程序包：
   rpm：
   OS Vendor：
   操作系统发行商提供的
   项目官方提供的

四 .Mysql的安装与配置

1. 配置Mysql 的yum 源

[root@Mysql-server ~]# cd /usr/src/
[root@Mysql-server src]# wget http://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.rpm 
[root@Mysql-server src]# ls
debug  kernels  mysql57-community-release-el7-10.noarch.rpm
[root@Mysql-server src]# yum install -y mysql57-community-release-el7-10.noarch.rpm
[root@Mysql-server src]# ls /etc/yum.repos.d/
cs.repo  mysql-community.repo  mysql-community-source.repo

2. 安装mysql 5.7

[root@Mysql-server ~]# yum -y install mysql-community-server mysql-community-client mysql-community-common mysql-community-deve
安装过程略...

3. 检查环境，启动服务

[root@Mysql-server ~]# systemctl stop firewalld
[root@Mysql-server ~]# systemctl disable firewalld
[root@Mysql-server ~]# setenforce 0
[root@Mysql-server ~]# systemctl start mysqld
[root@Mysql-server ~]# ss -anlt
State       Recv-Q Send-Q Local Address:Port                Peer Address:Port              
LISTEN      0      128                *:22                             *:*                  
LISTEN      0      100        127.0.0.1:25                             *:*                  
LISTEN      0      128               :::80                            :::*                  
LISTEN      0      128               :::22                            :::*                  
LISTEN      0      100              ::1:25                            :::*                  
LISTEN      0      80                :::3306      //mysql 服务端口已经监听                    :::* 

4. 配置Mysql
在日志文件中找出临时密码

[root@Mysql-server ~]# grep "password" /var/log/mysqld.log 
2018-08-17T12:46:26.744740Z 1 [Note] A temporary password is generated for root@localhost: soiFXZwVR7(y        //此处是随机密码，每次随机密码不一样

使用临时密码登陆mysql

[root@Mysql-server ~]# mysql -uroot -p       // -u  指定登录的用户    -p  指定登陆的密码 （可在-p后面接密码，为了安全性，不建议直接写密码）
Enter password:

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.23

Copyright (c) 2000, 2018, 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>      出现这个提示符说明成功登录了！

修改mysql 登录密码

mysql> set global validate_password_policy=0;       //
Query OK, 0 rows affected (0.00 sec)

mysql> set global validate_password_length=1;
Query OK, 0 rows affected (0.00 sec)

mysql> alter user 'root'@'localhost' identified by  'chen';
Query OK, 0 rows affected (0.00 sec)

mysql> quit
Bye

为了避免mysql 自动升级，需要卸载最开始安装的yum 源

[root@Mysql-server ~]# yum remove -y  mysql57-community-release.noarch

5. mysql工具的使用
语法：mysql [OPTIONS] [database]
常用的 OPTIONS：

-uUSERNAME       //指定用户名，默认为root
-hHOST                  //指定服务器主机，默认为localhost，推荐使用IP地址
-pPASSWORD        //指定用户密码
-P#                          //指定数据库监听的端口号，这里的# 需要用实际的端口号代替，例 ：-P3307
-V                            //查看当前使用的mysql版本
-e				//不登录mysql执行sql语句后退出，常用于脚本

[root@Mysql-server ~]# mysql -uroot -pchen -h127.0.0.1           
mysql: [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: 5.7.23 MySQL Community Server (GPL)

Copyright (c) 2000, 2018, 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> 

[root@Mysql-server ~]# mysql -uroot -p -h127.0.0.1 -e 'show databases;'
Enter password: 
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+

6. 服务器监听的两种socket地址

socket类型	说明
ip socket	默认监听在tcp的3306端口，支持远程通信
unix sock	监听在sock文件上（/tmp/mysql.sock，/var/lib/mysql/mysql.sock)，仅支持本地通信 ，server地址只能是：localhost ，127.0.0.1

7. mysql 数据库的操作
7.1 DDL操作
7.1.1 数据库操作
创建数据库chens

mysql> create database chens;
Query OK, 1 row affected (0.00 sec)

mysql> show databases;            // 查看有哪些数据库
+--------------------+
| Database           |
+--------------------+
| information_schema |
| chens              |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.00 sec)

删除数据库

mysql> drop database if exists chens;   
Query OK, 0 rows affected (0.00 sec)

mysql> drop database  chens;     // 这样是直接删除
Query OK, 0 rows affected (0.00 sec)

7.1.2 表操作
创建表
语法： CREATE TABLE table_name (col1 datatype 修饰符，col2 datatype 修饰符）ENGINE='存储引擎类型’；
创建一个表chens

mysql> use chens;     // 进入到chens 这个库里面，只有在库里面才能对表操作！
Database changed

mysql> create table chens(id int not null,name varchar(100) not null,age tinyint);
Query OK, 0 rows affected (0.05 sec)  
// int  这里表示整数，not null  这里表示不能为空，vachar（100）这里表示取的字符长度不能超过100     
**查看当前数据库有哪些表**
mysql> show tables;
+-----------------+
| Tables_in_chens |
+-----------------+
| chens           |
+-----------------+
1 row in set (0.00 sec)

**可查看表chens的结构！**
mysql> desc chens;
+-------+--------------+------+-----+---------+-------+
| Field | Type         | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+-------+
| id    | int(11)      | NO   |     | NULL    |       |
| name  | varchar(100) | NO   |     | NULL    |       |
| age   | tinyint(4)   | YES  |     | NULL    |       |
+-------+--------------+------+-----+---------+-------+
3 rows in set (0.01 sec) 

删除表
语法： DROP TABLE [ IF EXISTS ] ‘table_name’;
删除chens 表

mysql> drop table chens;
Query OK, 0 rows affected (0.01 sec

用户的操作

mysql用户账号由两部分组成，如‘USERNAME’@‘HOST’，表示此USERNAME只能从此HOST上远程登录，这里的（‘USERNAME’@‘HOST’）的HOST用于限制此用户可以通过哪些主机远程连接mysql程序，其值可设为：
IP 地址：192.168.168.10
通配符
.%：匹配任意长度的任意字符，常用于设置允许从任何主机登录
._：匹配任意单个字符

数据库用户创建
语法： CREATE USER ‘username’@‘host’ [IDENTIFIED BY ‘password’ ]；
创建数据库用户chens

mysql> create user 'chens'@'127.0.0.1' IDENTIFIED BY 'chens';
Query OK, 0 rows affected (0.01 sec)

使用新创建的用户密码登录

[root@localhost src]# mysql -uchens -pchens -h127.0.0.1
mysql: [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 6
Server version: 5.7.23 MySQL Community Server (GPL)
Copyright (c) 2000, 2018, 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> 

删除数据库用户
语法： DROP USER ‘username’@‘host’；
删除数据库用户chens

mysql> DROP USER 'chens'@'127.0.0.1';
Query OK, 0 rows affected (0.00 sec)

查看命令　SHOW
查看有哪些数据库

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| chens              |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.00 sec)

查看数据库里面有哪些表

mysql> use mysql;      //use  用于切换数据库
Database changed
mysql> show tables;
+---------------------------+
| Tables_in_mysql           |
+---------------------------+
| columns_priv              |
| db                        |
| engine_cost               |
| event                     |
| func                      |
| general_log               |
| gtid_executed             |
| help_category             |
| help_keyword              |
| help_relation             |
| help_topic                |
| innodb_index_stats        |
| innodb_table_stats        |
| ndb_binlog_index          |
| plugin                    |
| proc                      |
| procs_priv                |
| proxies_priv              |
| server_cost               |
| servers                   |
| slave_master_info         |
| slave_relay_log_info      |
| slave_worker_info         |
| slow_log                  |
| tables_priv               |
| time_zone                 |
| time_zone_leap_second     |
| time_zone_name            |
| time_zone_transition      |
| time_zone_transition_type |
| user                      |
+---------------------------+
31 rows in set (0.00 sec)

查看支持的所有字符集

mysql> show character set;
+----------+---------------------------------+---------------------+--------+
| Charset  | Description                     | Default collation   | Maxlen |
+----------+---------------------------------+---------------------+--------+
| big5     | Big5 Traditional Chinese        | big5_chinese_ci     |      2 |
| dec8     | DEC West European               | dec8_swedish_ci     |      1 |
| cp850    | DOS West European               | cp850_general_ci    |      1 |
| hp8      | HP West European                | hp8_english_ci      |      1 |
| koi8r    | KOI8-R Relcom Russian           | koi8r_general_ci    |      1 |
| latin1   | cp1252 West European            | latin1_swedish_ci   |      1 |
| latin2   | ISO 8859-2 Central European     | latin2_general_ci   |      1 |
| swe7     | 7bit Swedish                    | swe7_swedish_ci     |      1 |
| ascii    | US ASCII                        | ascii_general_ci    |      1 |
| ujis     | EUC-JP Japanese                 | ujis_japanese_ci    |      3 |
| sjis     | Shift-JIS Japanese              | sjis_japanese_ci    |      2 |
| hebrew   | ISO 8859-8 Hebrew               | hebrew_general_ci   |      1 |
| tis620   | TIS620 Thai                     | tis620_thai_ci      |      1 |
| euckr    | EUC-KR Korean                   | euckr_korean_ci     |      2 |
| koi8u    | KOI8-U Ukrainian                | koi8u_general_ci    |      1 |
| gb2312   | GB2312 Simplified Chinese       | gb2312_chinese_ci   |      2 |
| greek    | ISO 8859-7 Greek                | greek_general_ci    |      1 |
| cp1250   | Windows Central European        | cp1250_general_ci   |      1 |
| gbk      | GBK Simplified Chinese          | gbk_chinese_ci      |      2 |
| latin5   | ISO 8859-9 Turkish              | latin5_turkish_ci   |      1 |
| armscii8 | ARMSCII-8 Armenian              | armscii8_general_ci |      1 |
| utf8     | UTF-8 Unicode                   | utf8_general_ci     |      3 |
| ucs2     | UCS-2 Unicode                   | ucs2_general_ci     |      2 |
| cp866    | DOS Russian                     | cp866_general_ci    |      1 |
| keybcs2  | DOS Kamenicky Czech-Slovak      | keybcs2_general_ci  |      1 |
| macce    | Mac Central European            | macce_general_ci    |      1 |
| macroman | Mac West European               | macroman_general_ci |      1 |
| cp852    | DOS Central European            | cp852_general_ci    |      1 |
| latin7   | ISO 8859-13 Baltic              | latin7_general_ci   |      1 |
| utf8mb4  | UTF-8 Unicode                   | utf8mb4_general_ci  |      4 |
| cp1251   | Windows Cyrillic                | cp1251_general_ci   |      1 |
| utf16    | UTF-16 Unicode                  | utf16_general_ci    |      4 |
| utf16le  | UTF-16LE Unicode                | utf16le_general_ci  |      4 |
| cp1256   | Windows Arabic                  | cp1256_general_ci   |      1 |
| cp1257   | Windows Baltic                  | cp1257_general_ci   |      1 |
| utf32    | UTF-32 Unicode                  | utf32_general_ci    |      4 |
| binary   | Binary pseudo charset           | binary              |      1 |
| geostd8  | GEOSTD8 Georgian                | geostd8_general_ci  |      1 |
| cp932    | SJIS for Windows Japanese       | cp932_japanese_ci   |      2 |
| eucjpms  | UJIS for Windows Japanese       | eucjpms_japanese_ci |      3 |
| gb18030  | China National Standard GB18030 | gb18030_chinese_ci  |      4 |
+----------+---------------------------------+---------------------+--------+
41 rows in set (0.01 sec)

查看当前数据库支持的所有存储引擎

mysql> show engines;
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| Engine             | Support | Comment                                                        | Transactions | XA   | Savepoints |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| InnoDB             | DEFAULT | Supports transactions, row-level locking, and foreign keys     | YES          | YES  | YES        |
| MRG_MYISAM         | YES     | Collection of identical MyISAM tables                          | NO           | NO   | NO         |
| MEMORY             | YES     | Hash based, stored in memory, useful for temporary tables      | NO           | NO   | NO         |
| BLACKHOLE          | YES     | /dev/null storage engine (anything you write to it disappears) | NO           | NO   | NO         |
| MyISAM             | YES     | MyISAM storage engine                                          | NO           | NO   | NO         |
| CSV                | YES     | CSV storage engine                                             | NO           | NO   | NO         |
| ARCHIVE            | YES     | Archive storage engine                                         | NO           | NO   | NO         |
| PERFORMANCE_SCHEMA | YES     | Performance Schema                                             | NO           | NO   | NO         |
| FEDERATED          | NO      | Federated MySQL storage engine                                 | NULL         | NULL | NULL       |
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
9 rows in set (0.00 sec)

查看表的结构

mysql> desc user;
+------------------------+-----------------------------------+------+-----+-----------------------+-------+
| Field                  | Type                              | Null | Key | Default               | Extra |
+------------------------+-----------------------------------+------+-----+-----------------------+-------+
| Host                   | char(60)                          | NO   | PRI |                       |       |
| User                   | char(32)                          | NO   | PRI |                       |       |
| Select_priv            | enum('N','Y')                     | NO   |     | N                     
.....此处省略

查看某表的创建命令
语法： SHOW CREATE TABLE table_name；

mysql> show create table chens;

获取帮助

// 获取命令使用帮助
语法： HELP keyword；

mysql> help create table;    //获取创建表的帮助

INSERT语句
DML操作之增操作insert
在chens 这个表里面插入一条信息

mysql> insert into chens (id,name,age)value(1,'tom',20);
Query OK, 1 row affected (0.01 sec)

插入多条信息

mysql> insert into chens (id,name,age)values(1,'tom',20),(2,'jerry',23);
Query OK, 2 rows affected (0.00 sec)
Records: 2  Duplicates: 0  Warnings: 0

SELECT语句

字段column 表示法

表示符	代表什么？
*	所有字段
as	字段别名，如col1 AS alias1 当表名很长时间用别名代替

条件判断语句WHERE

操作类型	常用操作符
操作符	>,<,>=,<=,==,!= BETWEEN column# AND column# LIKE:模糊匹配 RLIKE：基于正则表达式进行匹配模式 IS NOT NULL：非空 IS NULL：空
条件逻辑操作	AND OR NOT

order by ：排序，默认为升序（ASC）

order by语句	意义
order by ‘column_name’	根据column_name进行升级排序
order by ’column_name’ DESC	根据column_name进行降序排列
order by ‘column_name’ LIMIT 2	根据column_name进行升序排列，并只取前两个结果
order by ‘column_name’ LIMIT 1,2	根据column_name 进行升序排列并略过第一个结果取后面的2个结果

SELECT 操作

查看chens 这个表的内容

mysql> select * from chens;
+----+-------+------+
| id | name  | age  |
+----+-------+------+
|  1 | tom   |   20 |
|  2 | jerry |   23 |
+----+-------+------+
2 rows in set (0.00 sec)

查看chens表里面，name这一栏信息

mysql> select name from chens;
+-------+
| name  |
+-------+
| tom   |
| jerry |
+-------+
2 rows in set (0.00 sec)

把chens这个表按照 age ，升序排列

mysql> select * from chens order by age;
+----+-------+------+
| id | name  | age  |
+----+-------+------+
|  1 | tom   |   20 |
|  2 | jerry |   23 |
+----+-------+------+
2 rows in set (0.00 sec)

把chens 这个表按照age 降序排列

mysql> select * from chens order by age desc ;
+----+-------+------+
| id | name  | age  |
+----+-------+------+
|  2 | jerry |   23 |
|  1 | tom   |   20 |
+----+-------+------+
2 rows in set (0.00 sec)

把chens这个表按照升序排列，取出age 前面2位

mysql> select * from chens order by age limit 2;
+----+-------+------+
| id | name  | age  |
+----+-------+------+
|  1 | tom   |   20 |
|  2 | jerry |   23 |
+----+-------+------+
2 rows in set (0.00 sec)

update 语句

修改chens 这个表里面tom 的age 为50

mysql> update chens set age = 50 where name= 'tom';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

delete 语句
删除操作 delete

删除chens 这张表里面id为7 的这条记录

mysql> delete from chens where id=1;
Query OK, 1 row affected (0.00 sec)

删除整张表的内容

mysql> delete from chens;
Query OK, 1 row affected (0.00 sec)

创建授权grant

权限类型	代表什么
ALL	所有权限
SELECT	读取内容的权限
INSERT	插入权限
update	更新内容权限
DELETE	删除内容权限

指定要操作的对象db_name.table_name

表示方法	意义
.	所有库的所有表
db_name	指定库的所有表
db_name.table_name	指定库的指定表

WITH GRANT OPTION：被授权的用户可将自己的权限副本转赠给其他用户，就是将自己的权限完全复制给另一个用户。不建议使用

授权chens用户在数据库本机上登录访问所有数据库

mysql> grant all on *.* to 'chens'@'localhost' identified by 'chen';
Query OK, 0 rows affected, 1 warning (0.01 sec)

mysql> grant all on *.* to 'chens'@'127.0.0.1' identified by 'chen';
Query OK, 0 rows affected, 1 warning (0.01 sec)

授权chens 用户在192.168.169.20 上远程登录访问chens数据库

mysql> grant all on chens.* to 'chens'@'192.168.169.20' identified by 'chen';
Query OK, 0 rows affected, 1 warning (0.00 sec)

授权chens 用户在所有位置上远程登录访问chens数据库

mysql> grant all on *.* to 'chens'@'%' identified by 'chen';
Query OK, 0 rows affected, 1 warning (0.00 sec)

查看当前登录用户的授权信息

mysql> show grants;
+---------------------------------------------------------------------+
| Grants for root@localhost                                           |
+---------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION |
| GRANT PROXY ON ''@'' TO 'root'@'localhost' WITH GRANT OPTION        |
+---------------------------------------------------------------------+
2 rows in set (0.00 sec)

查看指定用户chens的授权信息

mysql> show grants for chens;
+--------------------------------------------+
| Grants for chens@%                         |
+--------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'chens'@'%' |
+--------------------------------------------+
1 row in set (0.00 sec)

取消授权revoke

mysql> revoke all on *.* from  'chens'@'192.168.169.20';
Query OK, 0 rows affected (0.01 sec)

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

注意： MySQL服务进程启动时会读取mysql库中的所有授权表至内存中：
grant 或 revoke 等执行权限操作会保存于表中，mysql的服务进程会自动重读授权表，并更新至内存中
对于不能够或不能及时重读授权表的命令，可手动让mysql的服务进程重读授权表
重读授权表

mysql> flush privileges;
Query OK, 0 rows affected (0.00 sec)

mysql avg函数求平均值

MariaDB [chens]> select * from score;
+------------+-----------------+---------+------+---------+
| student_id | name            | chinese | Math | English |
+------------+-----------------+---------+------+---------+
|      21001 | jetlee          |      90 |   80 |      91 |
|      21002 | jackchan        |      80 |  100 |      70 |
|      21003 | Brucelee        |      70 |   58 |      90 |
|      21004 | Mlcheal jackson |      60 |   90 |      96 |
+------------+-----------------+---------+------+---------+

求出English 的平均数

MariaDB [chens]> select avg (English) from score;
+---------------+
| avg (English) |
+---------------+
|       86.7500 |
+---------------+
1 row in set (0.00 sec)

把平均使用GROUP BY 子句设置的各种记录，下面例子采取平均到一个人的所有相关记录，每个人的平均页打印纸

MariaDB [chens]> select name,avg (English) from score group by name;
+-----------------+---------------+
| name            | avg (English) |
+-----------------+---------------+
| Brucelee        |       90.0000 |
| jackchan        |       70.0000 |
| jetlee          |       91.0000 |
| Mlcheal jackson |       96.0000 |
+-----------------+---------------+
4 rows in set (0.00 sec)

mysql 数据求和

MariaDB [chens]> select sum(chinese+Math+English) as suma from score group by English  order by suma desc;
+------+
| suma |
+------+
|  261 |
|  250 |
|  246 |
|  218 |
+------+
4 rows in set (0.00 sec)