mysql基础
mysql基础
1. 关系型数据库介绍
1.1 数据结构模型
数据结构模型主要有：
- 层次模型
- 网状结构
- 关系模型
关系模型：
二维关系：row，column
数据库管理系统：DBMS
关系：Relational，RDBMS
1.2 RDBMS专业名词
常见的关系型数据库管理系统：
- MySQL：MySQL，MariaDB，Percona-Server
- PostgreSQL：简称为pgsql
- Oracle
- MSSQL
SQL：Structure Query Language，结构化查询语言
约束：constraint，向数据表提供的数据要遵守的限制
- 主键约束：一个或多个字段的组合，填入的数据必须能在本表中唯一标识本行。且必须提供数据，不能为空（NOT NULL）。
一个表只能存在一个 - 惟一键约束：一个或多个字段的组合，填入的数据必须能在本表中唯一标识本行。允许为空（NULL）
一个表可以存在多个 - 外键约束：一个表中的某字段可填入数据取决于另一个表的主键已有的数据
- 检查性约束
索引：将表中的一个或多个字段中的数据复制一份另存，并且这些数据需要按特定次序排序存储
1.3 关系型数据库的常见组件
关系型数据库的常见组件有：
- 数据库：database
- 表：table，由行（row）和列（column）组成
- 索引：index
- 视图：view
- 用户：user
- 权限：privilege
- 存储过程：procedure
- 存储函数：function
- 触发器：trigger
- 事件调度器：event scheduler
1.4 SQL语句
SQL语句有三种类型：
- DDL：Data Defination Language，数据定义语言
- DML：Data Manipulation Language，数据操纵语言
- DCL：Data Control Language，数据控制语言
| SQL语句类型 | 对应操作 |
|---|---|
| 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 REVOKE：移除授权 |
2. mysql安装与配置
2.1 mysql安装
mysql安装方式有三种：
- 源代码：编译安装
- 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
- 程序包管理器管理的程序包：
- rpm：有两种
- OS Vendor：操作系统发行商提供的
- 项目官方提供的
- rpm：有两种
- deb
#配置mysql的yum源
wget http://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.rpm
URL transformed to HTTPS due to an HSTS policy
--2022-07-25 13:26:26-- https://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.rpm
Resolving dev.mysql.com (dev.mysql.com)... 23.2.135.207, 2600:140b:2:18e::2e31, 2600:140b:2:1a7::2e31
Connecting to dev.mysql.com (dev.mysql.com)|23.2.135.207|:443... connected.
HTTP request sent, awaiting response... 302 Moved Temporarily
Location: https://repo.mysql.com//mysql57-community-release-el7-10.noarch.rpm [following]
--2022-07-25 13:26:27-- https://repo.mysql.com//mysql57-community-release-el7-10.noarch.rpm
Resolving repo.mysql.com (repo.mysql.com)... 184.30.152.230
Connecting to repo.mysql.com (repo.mysql.com)|184.30.152.230|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 25548 (25K) [application/x-redhat-package-manager]
Saving to: ‘mysql57-community-release-el7-10.noarch.rpm’
mysql57-community-r 100%[===================>] 24.95K --.-KB/s in 0s
2022-07-25 13:26:28 (101 MB/s) - ‘mysql57-community-release-el7-10.noarch.rpm’ saved [25548/25548]
[root@localhost ~]# ls
anaconda-ks.cfg apr-util-1.6.1.tar.gz
apr-1.7.0 httpd-2.4.54
apr-1.7.0.tar.gz httpd-2.4.54.tar.gz
apr-util-1.6.1 mysql57-community-release-el7-10.noarch.rpm
#安装mysql5.7
[root@localhost ~]# rpm -Uvh mysql57-community-release-el7-10.noarch.rpm
warning: mysql57-community-release-el7-10.noarch.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY
Verifying... ################################# [100%]
Preparing... ################################# [100%]
Updating / installing...
1:mysql57-community-release-el7-10 ################################# [10
//禁用mysql
[root@localhost ~]# yum module disable mysql
MySQL Connectors Community 26 kB/s | 49 kB 00:01
MySQL Tools Community 183 kB/s | 651 kB 00:03
MySQL 5.7 Community Server 172 kB/s | 2.6 MB 00:15
Dependencies resolved.
================================================================================
Package Architecture Version Repository Size
================================================================================
Disabling modules:
mysql
Transaction Summary
================================================================================
Is this ok [y/N]: y
Complete!
[root@localhost ~]# yum -y install mysql-community-server mysql-community-client mysql-community-common mysql-community-devel --nogpgcheck
Last metadata expiration check: 0:00:38 ago on Mon 25 Jul 2022 01:28:07 PM CST.
Dependencies resolved.
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
mysql-community-client x86_64 5.7.38-1.el7 mysql57-community 28 M
mysql-community-common x86_64 5.7.38-1.el7 mysql57-community 311 k
mysql-community-devel x86_64 5.7.38-1.el7 mysql57-community 4.2 M
mysql-community-server x86_64 5.7.38-1.el7 mysql57-community 178 M
Installing dependencies:
mysql-community-libs x86_64 5.7.38-1.el7 mysql57-community 2.6 M
ncurses-compat-libs x86_64 6.1-9.20180224.el8 baseos 328 k
net-tools x86_64 2.0-0.52.20160912git.el8 baseos 322 k
略......
2.2 mysql配置
#启动mysql并设置开机自动启动
[root@localhost ~]# systemctl enable --now mysqld
[root@localhost ~]# systemctl status mysqld
● mysqld.service - MySQL Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor pres>
Active: active (running) since Mon 2022-07-25 13:31:13 CST; 6s ago
Docs: man:mysqld(8)
http://dev.mysql.com/doc/refman/en/using-systemd.html
Process: 54353 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mys>
Process: 54304 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=>
Main PID: 54356 (mysqld)
Tasks: 27 (limit: 49262)
Memory: 301.7M
CGroup: /system.slice/mysqld.service
└─54356 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysq>
Jul 25 13:31:11 localhost.localdomain systemd[1]: Starting MySQL Server...
Jul 25 13:31:13 localhost.localdomain systemd[1]: Started MySQL Server.
#确保3306端口已经监听起来
[root@localhost ~]# ss -antl
State Recv-Q Send-Q Local Address:Port Peer Address:Port Process
LISTEN 0 128 0.0.0.0:22 0.0.0.0:*
LISTEN 0 128 [::]:22 [::]:*
LISTEN 0 80 *:3306 *:*
#在日志文件中找出临时密码
[root@localhost ~]# grep "password" /var/log/mysqld.log
2022-07-25T05:31:11.960829Z 1 [Note] A temporary password is generated for root@localhost: l0edhV9ow5&?
#使用获取到的临时密码登录mysql
[root@localhost ~]# mysql -uroot -p
Enter password: //此处输入密码，可以直接复制你的密码粘贴至此处，也可手动输入
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.38
Copyright (c) 2000, 2022, Oracle and/or its affiliates.
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> //看到有这样的标识符则表示成功登录了
//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 'shushao1234561';
Query OK, 0 rows affected (0.00 sec)
mysql> quit
Bye
//为避免mysql自动升级，这里需要卸载最开始安装的yum源
[root@localhost ~]# rpm -e mysql57-community-release
3. mysql的程序组成
-
客户端
-
mysql：CLI交互式客户端程序
-
mysql_secure_installation：安全初始化，强烈建议安装完以后执行此命令
-
mysqldump：mysql备份工具
-
mysqladmin
-
服务器端
-
mysqld
3.1 mysql工具使用
//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 //指定用户的密码
-P# //指定数据库监听的端口，这里的#需用实际的端口号代替，如-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@localhost ~]# mysql -V
mysql Ver 14.14 Distrib 5.7.38, for Linux (x86_64) using EditLine wrapper
[root@localhost ~]# mysql -uroot -pshushao1234561
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 5
Server version: 5.7.38 MySQL Community Server (GPL)
Copyright (c) 2000, 2022, Oracle and/or its affiliates.
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> exit
Bye
//注意，不推荐直接在命令行里直接用-pPASSWORD的方式登录，而是使用-p选项，然后交互式输入密码
[root@localhost ~]# mysql -uroot -pshushao1234561 -h 127.0.0.1
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 9
Server version: 5.7.38 MySQL Community Server (GPL)
Copyright (c) 2000, 2022, Oracle and/or its affiliates.
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> exit
Bye
[root@localhost ~]# mysql -uroot -p -h 127.0.0.1 -e 'SHOW DATABASES;'
Enter password:
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
3.2 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 |
4. mysql数据库操作
4.1 DDL操作
4.1.1 数据库操作
//创建数据库
//语法：CREATE DATABASE [IF NOT EXISTS] 'DB_NAME';
//创建数据库shuhsaoa
[root@localhost ~]# mysql -uroot -pshushao1234561 -h 127.0.0.1
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 11
Server version: 5.7.38 MySQL Community Server (GPL)
Copyright (c) 2000, 2022, Oracle and/or its affiliates.
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> CREATE DATABASE IF NOT EXISTS shushaoa;
Query OK, 1 row affected (0.01 sec)
//查看当前实例有哪些数据库
mysql> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| shushaoa |
| sys |
+--------------------+
5 rows in set (0.00 sec)
//删除数据库
//语法：DROP DATABASE [IF EXISTS] 'DB_NAME';
//删除数据库wangqingge
mysql> DROP DATABASE IF EXISTS shushaoa;
Query OK, 0 rows affected (0.00 sec)
mysql> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.00 sec)
4.1.2 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';
//在数据库shushaoa里创建表shushaoa
mysql> CREATE DATABASE shushaoa;
Query OK, 1 row affected (0.00 sec)
mysql> use shushaoa;
Database changed
mysql> CREATE TABLE shushao (id int NOT NULL,name VARCHAR(100) NOT NULL,age tinyint);
Query OK, 0 rows affected (0.00 sec)
//查看当前数据库有哪些表
mysql> SHOW TABLES;
+--------------------+
| Tables_in_shushaoa |
+--------------------+
| shushao |
+--------------------+
1 row in set (0.00 sec)
mysql>
//删除表
//语法：DROP TABLE [ IF EXISTS ] 'table_name';
//删除表shushao
mysql> DROP TABLE shushao;
Query OK, 0 rows affected (0.01 sec)
mysql> SHOW TABLES;
Empty set (0.00 sec)
4.1.3 用户操作
mysql用户帐号由两部分组成，如'USERNAME'@'HOST'，表示此USERNAME只能从此HOST上远程登录
这里（'USERNAME'@'HOST'）的HOST用于限制此用户可通过哪些主机远程连接mysql程序，其值可为：
- IP地址，如：172.16.12.129
- 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shushao
mysql> CREATE USER 'shushao'@'127.0.0.1' IDENTIFIED BY 'shushao1234561';
Query OK, 0 rows affected (0.00 sec)
//使用新创建的用户和密码登录
[root@localhost ~]# mysql -ushushao -pshushao1234561 -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 13
Server version: 5.7.38 MySQL Community Server (GPL)
Copyright (c) 2000, 2022, Oracle and/or its affiliates.
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';
mysql> DROP USER 'shushao'@'127.0.0.1';
Query OK, 0 rows affected (0.00 sec)
4.1.4 查看命令SHOW
mysql> SHOW CHARACTER SET; //查看支持的所有字符集
+----------+---------------------------------+---------------------+--------+
| 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 (0.00 sec)
mysql> SHOW ENGINES; //查看当前数据库支持的所有存储引擎
+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+
| 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)
mysql> SHOW DATABASES; //查看数据库信息
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| shushaoa |
| sys |
+--------------------+
5 rows in set (0.00 sec)
mysql> SHOW TABLES FROM shushaoa; //不进入某数据库而列出其包含的所有表
mysql> SHOW TABLES FROM shushaoa;
Empty set (0.00 sec)
//查看表结构
//语法：DESC [db_name.]table_name;
mysql> DESC shushaoa;shushao;
+-------+--------------+------+-----+---------+-------+
| 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 (0.03 sec)
//查看某表的创建命令
//语法：SHOW CREATE TABLE table_name;
mysql> SHOW CREATE TABLE shushaoa.shushao;
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| wangqing | CREATE TABLE `wangqing` (
`id` int(11) NOT NULL,
`name` varchar(100) NOT NULL,
`age` tinyint(4) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
//查看某表的状态
//语法：SHOW TABLE STATUS LIKE 'table_name'\G
mysql> shushaoa; //进入数据库shushaoa
Database changed
mysql> SHOW TABLE STATUS LIKE 'shushao'\G //查看wangqing表的状态
*************************** 1. row ***************************
Name: wangqing
Engine: InnoDB
Version: 10
Row_format: Dynamic
Rows: 0
Avg_row_length: 0
Data_length: 16384
Max_data_length: 0
Index_length: 0
Data_free: 0
Auto_increment: NULL
Create_time: 2018-08-13 00:53:21
Update_time: NULL
Check_time: NULL
Collation: latin1_swedish_ci
Checksum: NULL
Create_options:
Comment:
1 row in set (0.00 sec)
4.1.5 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
mysql> HELP CREATE TABLE;
Name: 'CREATE TABLE'
Description:
Syntax:
CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
(create_definition,...)
[table_options]
[partition_options]
CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
[(create_definition,...)]
[table_options]
[partition_options]
[IGNORE | REPLACE]
[AS] query_expression
CREATE [TEMPORARY] TABLE [IF NOT EXISTS] tbl_name
{ LIKE old_tbl_name | (LIKE old_tbl_name) }
create_definition: {
col_name column_definition
| {INDEX | KEY} [index_name] [index_type] (key_part,...)
[index_option] ...
| {FULLTEXT | SPATIAL} [INDEX | KEY] [index_name] (key_part,...)
[index_option] ...
| [CONSTRAINT [symbol]] PRIMARY KEY
[index_type] (key_part,...)
[index_option] ...
| [CONSTRAINT [symbol]] UNIQUE [INDEX | KEY]
[index_name] [index_type] (key_part,...)
[index_option] ...
| [CONSTRAINT [symbol]] FOREIGN KEY
[index_name] (col_name,...)
reference_definition
| CHECK (expr)
}
column_definition: {
data_type [NOT NULL | NULL] [DEFAULT default_value]
[AUTO_INCREMENT] [UNIQUE [KEY]] [[PRIMARY] KEY]
[COMMENT 'string']
[COLLATE collation_name]
[COLUMN_FORMAT {FIXED | DYNAMIC | DEFAULT}]
[STORAGE {DISK | MEMORY}]
[reference_definition]
| data_type
[COLLATE collation_name]
[GENERATED ALWAYS] AS (expr)
[VIRTUAL | STORED] [NOT NULL | NULL]
[UNIQUE [KEY]] [[PRIMARY] KEY]
[COMMENT 'string']
[reference_definition]
}
data_type:
(see https://dev.mysql.com/doc/refman/5.7/en/data-types.html)
......
......
4.2 DML操作
DML操作包括增(INSERT)、删(DELETE)、改(UPDATE)、查(SELECT)，均属针对表的操作。
4.2.1 INSERT语句
//DML操作之增操作insert
//语法：INSERT [INTO] table_name [(column_name,...)]
{VALUES | VALUE} (value1,...),(...),...
mysql> use shushaoa;
Database changed
mysql> INSERT INTO shushao (id,name,age) VALUE (1,'tom',20); //一次插入一条记录
Query OK, 1 row affected (0.01 sec)
mysql> INSERT INTO wangqing (id,name,age) VALUES (2,'jerry',23),(3,'wangqing',25),(4,'sean',28),(5,'zhangshan',26),(6,'zhangshan',20),(7,'lisi',NULL); //一次插入多条记录
Query OK, 4 rows affected (0.01 sec)
Records: 4 Duplicates: 0 Warnings: 0
4.2.2 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模式匹配IS NOT NULL：非空IS NULL：空 |
| 条件逻辑操作 | ANDORNOT |
ORDER BY：排序，默认为升序（ASC）
| ORDER BY语句 | 意义 |
|---|---|
| ORDER BY ‘column_name' | 根据column_name进行升序排序 |
| ORDER BY 'column_name' DESC | 根据column_name进行降序排序 |
| ORDER BY ’column_name' LIMIT 2 | 根据column_name进行升序排序,并只取前2个结果 |
| ORDER BY ‘column_name' LIMIT 1,2 | 根据column_name进行升序排序,并且略过第1个结果取后面的2个结果 |
//DML操作之查操作select
//语法：SELECT column1,column2,... FROM table_name [WHERE clause] [ORDER BY 'column_name' [DESC]] [LIMIT [m,]n];
mysql> use shushaoa;
Database changed
mysql> select * from shushao;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> SELECT name FROM wangqing;
+-----------+
| name |
+-----------+
| tom |
| jerry |
| wangqing |
| sean |
| zhangshan |
| zhangshan |
| lisi |
+-----------+
7 rows in set (0.01 sec)
mysql> SELECT * FROM shushao ORDER BY age;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 7 | lisi | NULL |
| 1 | tom | 20 |
| 6 | zhangshan | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 5 | zhangshan | 26 |
| 4 | sean | 28 |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> SELECT * FROM shushao ORDER BY age DESC;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 3 | wangqing | 25 |
| 2 | jerry | 23 |
| 1 | tom | 20 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> SELECT * FROM shushao ORDER BY age limit 2;
+----+------+------+
| id | name | age |
+----+------+------+
| 7 | lisi | NULL |
| 1 | tom | 20 |
+----+------+------+
2 rows in set (0.00 sec)
mysql> SELECT * FROM shushao ORDER BY age limit 1,2;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 6 | zhangshan | 20 |
+----+-----------+------+
2 rows in set (0.00 sec)
mysql> SELECT * FROM shushao WHERE age >= 25;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
+----+-----------+------+
3 rows in set (0.00 sec)
mysql> SELECT * FROM shushao WHERE age >= 25 AND name = 'zhangshan';
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 5 | zhangshan | 26 |
+----+-----------+------+
1 row in set (0.00 sec)
mysql> SELECT * FROM shushao WHERE age BETWEEN 23 and 28;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
+----+-----------+------+
4 rows in set (0.00 sec)
mysql> select * from shushao where age is not null;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
+----+-----------+------+
6 rows in set (0.00 sec)
mysql> select * from shushao where age is null;
+----+------+------+
| id | name | age |
+----+------+------+
| 7 | lisi | NULL |
+----+------+------+
1 row in set (0.00 sec)
4.2.3 update语句
//DML操作之改操作update
//语法：UPDATE table_name SET column1 = new_value1[,column2 = new_value2,...] [WHERE clause] [ORDER BY 'column_name' [DESC]] [LIMIT [m,]n];
mysql> select * from shushao;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> update shushao set age = 30 where name = 'lisi';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from wangqing where name = 'lisi';
+----+------+------+
| id | name | age |
+----+------+------+
| 7 | lisi | 30 |
+----+------+------+
1 row in set (0.00 sec)
4.2.4 delete语句
//DML操作之删操作delete
//语法：DELETE FROM table_name [WHERE clause] [ORDER BY 'column_name' [DESC]] [LIMIT [m,]n];
mysql> select * from shushao;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | shushao | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | 30 |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> delete fromshushao where id = 7; //删除某条记录
Query OK, 1 row affected (0.00 sec)
mysql> select * from shushao;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | shushao | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
+----+-----------+------+
6 rows in set (0.00 sec)
mysql> delete from shushao; //删除整张表的内容
Query OK, 6 rows affected (0.00 sec)
mysql> select * from wangqing;
Empty set (0.00 sec)
mysql> desc wangqing;
+-------+--------------+------+-----+---------+-------+
| 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 (0.00 sec)
4.2.5 truncate语句
truncate与delete的区别：
| 语句类型 | 特点 |
|---|---|
| delete | DELETE删除表内容时仅删除内容，但会保留表结构，DELETE语句每次删除一行，并在事务日志中为所删除的每行记录一项，可以通过回滚事务日志恢复数据，非常占用空间 |
| truncate | 删除表中所有数据，且无法恢复，表结构、约束和索引等保持不变，新添加的行计数值重置为初始值，执行速度比DELETE快，且使用的系统和事务日志资源少，通过释放存储表数据所用的数据页来删除数据，并且只在事务日志中记录页的释放,对于有外键约束引用的表，不能使用TRUNCATE TABLE删除数据，不能用于加入了索引视图的表 |
//语法：TRUNCATE table_name;
mysql> select * from shushao;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | shushao | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> truncate shushao;
Query OK, 0 rows affected (0.01 sec)
mysql> select * from shushao;
Empty set (0.00 sec)
mysql> desc wangqing;
+-------+--------------+------+-----+---------+-------+
| 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 (0.00 sec)
4.3 DCL操作
4.3.1 创建授权grant
权限类型(priv_type)
| 权限类型 | 代表什么？ |
|---|---|
| ALL | 所有权限 |
| SELECT | 读取内容的权限 |
| INSERT | 插入内容的权限 |
| UPDATE | 更新内容的权限 |
| DELETE | 删除内容的权限 |
指定要操作的对象db_name.table_name
| 表示方式 | 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，说白点就是将自己的权限完全复制给另一个用户。不建议使用。
GRANT priv_type,... ON [object_type] db_name.table_name TO ‘username'@'host' [IDENTIFIED BY 'password'] [WITH GRANT OPTION];
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| shushaoa |
+--------------------+
5 rows in set (0.00 sec)
//授权wangqing用户在数据库本机上登录访问所有数据库
mysql> GRANT ALL ON *.* TO 'shushao'@'localhost' IDENTIFIED BY 'shushao1234561';
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> GRANT ALL ON *.* TO 'shushao'@'127.0.0.1' IDENTIFIED BY 'shushao1234561';
Query OK, 0 rows affected, 1 warning (0.00 sec)
//授权wangqing用户在172.16.12.129上远程登录访问wangqingge数据库
mysql> GRANT ALL ON shushaoa.* TO 'shushao'@'172.16.12.129' IDENTIFIED BY 'shushao1234561';
Query OK, 0 rows affected, 1 warning (0.00 sec)
//授权wangqing用户在所有位置上远程登录访问wangqingge数据库
mysql> GRANT ALL ON *.* TO 'shushao'@'%' IDENTIFIED BY 'shushao1234561';
Query OK, 0 rows affected, 1 warning (0.00 sec)
4.3.2 查看授权
//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wangqing的授权信息
mysql> SHOW GRANTS FOR shushao;
+-----------------------------------------------+
| Grants for shushao@% |
+-----------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'shushao'@'%' |
+-----------------------------------------------+
1 row in set (0.00 sec)
mysql> SHOW GRANTS FOR 'shushao'@'localhost';
+-------------------------------------------------------+
| Grants for shushao@localhost |
+-------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'shushao'@'localhost' |
+-------------------------------------------------------+
1 row in set (0.00 sec)
mysql> SHOW GRANTS FOR 'shushao'@'127.0.0.1';
+-------------------------------------------------------+
| Grants for shushao@127.0.0.1 |
+-------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'shushao'@'127.0.0.1' |
+-------------------------------------------------------+
1 row in set (0.00 sec)
4.3.3 取消授权REVOKE
//语法：REVOKE priv_type,... ON db_name.table_name FROM 'username'@'host';
mysql> REVOKE ALL ON *.* FROM 'shushao'@'172.168.237.134';
Query OK, 0 rows affected (0.00 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
mysql> FLUSH PRIVILEGES;
MySQL 数据类型
MySQL中定义数据字段的类型对数据库的优化是非常重要的。MySQL支持多种类型，大致可以分为三类：数值、日期/时间和字符串(字符)类型。
数值类型
MySQL支持所有标准SQL数值数据类型。这些类型包括严格数值数据类型(INTEGER、SMALLINT、DECIMAL和NUMERIC)，以及近似数值数据类型(FLOAT、REAL和DOUBLE PRECISION)。
关键字INT是INTEGER的同义词，关键字DEC是DECIMAL的同义词。
BIT数据类型保存位字段值，并且支持MyISAM、MEMORY、InnoDB和BDB表。作为SQL标准的扩展，MySQL也支持整数类型TINYINT、MEDIUMINT和BIGINT。下面的表显示了需要的每个整数类型的存储和范围
日期和时间类型
表示时间值的日期和时间类型为DATETIME、DATE、TIMESTAMP、TIME和YEAR。每个时间类型有一个有效值范围和一个"零"值，当指定不合法的MySQL不能表示的值时使用"零"值。TIMESTAMP类型有专有的自动更新特性，将在后面描述
字符串类型
字符串类型指CHAR、VARCHAR、BINARY、VARBINARY、BLOB、TEXT、ENUM和SET。该节描述了这些类型如何工作以及如何在查询中使用这些类型。
注意：
char(n) 和 varchar(n) 中括号中 n 代表字符的个数，并不代表字节个数，比如 CHAR(30) 就可以存储 30 个字符。
CHAR 和 VARCHAR 类型类似，但它们保存和检索的方式不同。它们的最大长度和是否尾部空格被保留等方面也不同。在存储或检索过程中不进行大小写转换。
BINARY 和 VARBINARY 类似于 CHAR 和 VARCHAR，不同的是它们包含二进制字符串而不要非二进制字符串。也就是说，它们包含字节字符串而不是字符字符串。这说明它们没有字符集，并且排序和比较基于列值字节的数值值。
BLOB 是一个二进制大对象，可以容纳可变数量的数据。有 4 种 BLOB 类型：TINYBLOB、BLOB、MEDIUMBLOB 和 LONGBLOB。它们区别在于可容纳存储范围不同。
有 4 种 TEXT 类型：TINYTEXT、TEXT、MEDIUMTEXT 和 LONGTEXT。对应的这 4 种 BLOB 类型，可存储的最大长度不同，可根据实际情况选择。
浙公网安备 33010602011771号