mysql 基础

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摘要

第一种方式:使用yum进行安装
第二种方式:yum安装mariadb
yum install -y mariadb*


mysql基础


mysql安装

第一种方式:使用yum进行安装
第二种方式:yum安装mariadb
yum install -y mariadb*

配置mysql的yum源: [root@lnh ~]# wget http://dev.mysql.com/get/mysql57-community-release-el7-11.noarch.rpm --2022-07-25 17:03:13--  http://dev.mysql.com/get/mysql57-community-release-el7-11.noarch.rpm Resolving dev.mysql.com (dev.mysql.com)... 184.29.181.90, 2600:1402:b800:1194::2e31, 2600:1402:b800:118f::2e31 Connecting to dev.mysql.com (dev.mysql.com)|184.29.181.90|:80... connected. HTTP request sent, awaiting response... 301 Moved Permanently Location: https://dev.mysql.com/get/mysql57-community-release-el7-11.noarch.rpm [following] --2022-07-25 17:03:13--  https://dev.mysql.com/get/mysql57-community-release-el7-11.noarch.rpm Connecting to dev.mysql.com (dev.mysql.com)|184.29.181.90|:443... connected. HTTP request sent, awaiting response... 302 Moved Temporarily Location: https://repo.mysql.com//mysql57-community-release-el7-11.noarch.rpm [following] --2022-07-25 17:03:14--  https://repo.mysql.com//mysql57-community-release-el7-11.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: 25680 (25K) [application/x-redhat-package-manager] Saving to: ‘mysql57-community-release-el7-11.noarch.rpm’  mysql57-community- 100%[================>]  25.08K   125KB/s    in 0.2s      2022-07-25 17:03:15 (125 KB/s) - ‘mysql57-community-release-el7-11.noarch.rpm’ saved [25680/25680] [root@lnh ~]# rpm -Uvh  mysql57-community-release-el7-11.noarch.rpm warning: mysql57-community-release-el7-11.noarch.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY Verifying...                          ################################# [100%] Preparing...                          ################################# [100%] Updating / installing...    1:mysql57-community-release-el7-11 ################################# [100%] [root@lnh ~]# rpm -Uvh  mysql57-community-release-el7-11.noarch.rpm warning: mysql57-community-release-el7-11.noarch.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY Verifying...                          ################################# [100%] Preparing...                          ################################# [100%] Updating / installing...    1:mysql57-community-release-el7-11 ################################# [100%] [root@lnh ~]# dnf module disable mysql    //禁用mysql MySQL Connectors Community                   47 kB/s |  49 kB     00:01     MySQL Tools Community                       257 kB/s | 651 kB     00:02     MySQL 5.7 Community Server                  817 kB/s | 2.6 MB     00:03     Dependencies resolved. ============================================================================  Package          Architecture    Version            Repository        Size ============================================================================ Disabling modules:  mysql                                                                       Transaction Summary ============================================================================  Is this ok [y/N]: y Complete! [root@lnh ~]# dnf -y install mysql-community-server mysql-community-client mysql-community-common mysql-community-devel --nogpgcheck   //不验证合法性进行下载 [root@lnh ~]# systemctl enable --now mysqld   //设置开机自启 [root@lnh ~]# systemctl status mysqld.service //查看状态 ● mysqld.service - MySQL Server    Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor >    Active: active (running) since Mon 2022-07-25 17:36:19 CST; 12s ago      Docs: man:mysqld(8)            http://dev.mysql.com/doc/refman/en/using-systemd.html   Process: 67864 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run>   Process: 67814 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, sta>  Main PID: 67866 (mysqld)     Tasks: 27 (limit: 12221)    Memory: 310.2M    CGroup: /system.slice/mysqld.service            └─67866 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/>  Jul 25 17:36:17 lnh systemd[1]: Starting MySQL Server... Jul 25 17:36:19 lnh systemd[1]: Started MySQL Server. [root@lnh ~]# ss -antl   //查看3306端口是否出现 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                  *:80                  *:*               LISTEN  0       128               [::]:22               [::]:*               LISTEN  0       80                   *:3306                *:*               [root@lnh ~]# grep "password" /var/log/mysqld.log  2022-07-25T09:36:17.891633Z 1 [Note] A temporary password is generated for root@localhost: eNGwhYkrz3_( //在日志文件中找出临时密码 [root@lnh ~]# mysql -uroot -p   //使用临时密码登录 Enter password:  Welcome to the MySQL monitor.  Commands end with ; or g. Your MySQL connection id is 5 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. //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 'xbz123'; Query OK, 0 rows affected (0.00 sec)  mysql> quit Bye [root@lnh ~]# mysql -uroot -pxbz123    //验证密码修改成功 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: 5.7.38 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>  [root@lnh ~]# rpm -qa |grep mysql mysql-community-client-5.7.38-1.el7.x86_64 mysql57-community-release-el7-11.noarch mysql-community-common-5.7.38-1.el7.x86_64 mysql-community-server-5.7.38-1.el7.x86_64 mysql-community-devel-5.7.38-1.el7.x86_64 mysql-community-libs-5.7.38-1.el7.x86_64 [root@lnh ~]# rpm -e mysql57-community-release-el7-11.noarch //卸载这个包防止其更新 

虚拟格式化

[root@lnh ~]# mysql_secure_installation   Securing the MySQL server deployment.  Enter password for user root:    //之前的密码 The 'validate_password' plugin is installed on the server. The subsequent steps will run with the existing configuration of the plugin. Using existing password for root.  Estimated strength of the password: 50  Change the password for root ? ((Press y|Y for Yes, any other key for No) : y  New password:    //新密码  Re-enter new password:     //再次输入  Estimated strength of the password: 50  Do you wish to continue with the password provided?(Press y|Y for Yes, any other key for No) : y By default, a MySQL installation has an anonymous user, allowing anyone to log into MySQL without having to have a user account created for them. This is intended only for testing, and to make the installation go a bit smoother. You should remove them before moving into a production environment.  Remove anonymous users? (Press y|Y for Yes, any other key for No) : y Success.   Normally, root should only be allowed to connect from 'localhost'. This ensures that someone cannot guess at the root password from the network.  Disallow root login remotely? (Press y|Y for Yes, any other key for No) : n //不让ssh远程连接数据库  ... skipping. By default, MySQL comes with a database named 'test' that anyone can access. This is also intended only for testing, and should be removed before moving into a production environment.   Remove test database and access to it? (Press y|Y for Yes, any other key for No) : y  - Dropping test database... Success.   - Removing privileges on test database... Success.  Reloading the privilege tables will ensure that all changes made so far will take effect immediately.  Reload privilege tables now? (Press y|Y for Yes, any other key for No) : y Success.  All done!   

mysql工具使用

[root@lnh ~]# mysql -V mysql  Ver 14.14 Distrib 5.7.38, for Linux (x86_64) using  EditLine wrapper //查看当前版本 [root@lnh ~]# mysql -uroot -pxbz123 -h127.0.0.1     //-h 指定服务器主机,默认为localhost,推荐使用ip地址  //直接在命令行输入密码登录 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 10 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> quit Bye        [root@lnh ~]# mysql -uroot -p  -h127.0.0.1      Enter password:  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>  //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@lnh ~]# mysql -uroot -p  -h127.0.0.1 -e 'SHOW DATABASES;' Enter password:  +--------------------+ | Database           | +--------------------+ | information_schema | | mysql              | | performance_schema | | sys                | +--------------------+ //不登录mysql查看有哪些数据库 

数据库操作

mysql> create database tushanbu; Query OK, 1 row affected (0.00 sec) //创建数据库 mysql> show databases; +--------------------+ | Database           | +--------------------+ | information_schema | | mysql              | | performance_schema | | sys                | | tushanbu           | +--------------------+ 5 rows in set (0.00 sec) //查看数据库 mysql> drop database tushanbu     -> ; Query OK, 0 rows affected (0.01 sec) //删除数据库 mysql> show databases; +--------------------+ | Database           | +--------------------+ | information_schema | | mysql              | | performance_schema | | sys                | +--------------------+ 4 rows in set (0.00 sec) //查看数据库 

表操作

mysql> create database tushanbu; Query OK, 1 row affected (0.00 sec) //创建数据库 mysql> use tushanbu;  //进入数据库 Database changed mysql> create table tsb(id int not null,name varchar(100) not null,age int); Query OK, 0 rows affected (0.02 sec) //创建表 mysql> desc tsb;  //查看结构 +-------+--------------+------+-----+---------+-------+ | Field | Type         | Null | Key | Default | Extra | +-------+--------------+------+-----+---------+-------+ | id    | int(11)      | NO   |     | NULL    |       | | name  | varchar(100) | NO   |     | NULL    |       | | age   | int(11)      | YES  |     | NULL    |       | +-------+--------------+------+-----+---------+-------+ 3 rows in set (0.01 sec) mysql> show tables; +--------------------+ | Tables_in_tushanbu | +--------------------+ | tsb                | +--------------------+ 1 row in set (0.00 sec) //查看表 mysql> drop table tsb; Query OK, 0 rows affected (0.01 sec) //删除表 mysql> show tables; Empty set (0.00 sec) //查看 

用户操作

mysql> create user 'lnh'@'127.0.0.1'  identified by 'xbz123'; Query OK, 0 rows affected (0.01 sec) //创建数据库用户lnh mysql> quit Bye [root@lnh ~]# mysql -ulnh -pxbz123 -h127.0.0.1 //使用新创建的用户和密码登录 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 15 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> [root@lnh ~]# mysql -uroot -p Enter password:  Welcome to the MySQL monitor.  Commands end with ; or g. Your MySQL connection id is 16 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> drop user 'lnh'@'127.0.0.1';   //删除数据库用户 Query OK, 0 rows affected (0.00 sec)  mysql> quit Bye [root@lnh ~]#  mysql -ulnh -pxbz123 -h127.0.0.1 mysql: [Warning] Using a password on the command line interface can be insecure. ERROR 1045 (28000): Access denied for user 'lnh'@'localhost' (using password: YES //已经删除 

查看命令SHOW

[root@lnh ~]# mysql -uroot -p Enter password:  Welcome to the MySQL monitor.  Commands end with ; or g. Your MySQL connection id is 18 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> 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 | ... 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;   //查看数据库的信息 +--------------------+ | Database           | +--------------------+ | information_schema | | mysql              | | performance_schema | | sys                | | tushanbu           | +--------------------+ 5 rows in set (0.00 sec) mysql> show tables from tushanbu;  //不进去其数据库查看表 +--------------------+ | Tables_in_tushanbu | +--------------------+ | tsb                | +--------------------+ 1 row in set (0.00 sec) mysql> desc tushanbu.tsb;   //不进入数据库查看数据库表的结构 +-------+--------------+------+-----+---------+-------+ | Field | Type         | Null | Key | Default | Extra | +-------+--------------+------+-----+---------+-------+ | id    | int(11)      | NO   |     | NULL    |       | | name  | varchar(100) | NO   |     | NULL    |       | | age   | int(11)      | YES  |     | NULL    |       | +-------+--------------+------+-----+---------+-------+ 3 rows in set (0.00 sec) mysql> show create table tushanbu.tsb;  //创建某表的创建命令 +-------+---------------------------------------------------------------------------------------------------------------------------------------------------+ | Table | Create Table                                                                                                                                      | +-------+---------------------------------------------------------------------------------------------------------------------------------------------------+ | tsb   | CREATE TABLE `tsb` (   `id` int(11) NOT NULL,   `name` varchar(100) NOT NULL,   `age` int(11) DEFAULT NULL ) ENGINE=InnoDB DEFAULT CHARSET=latin1 | +-------+---------------------------------------------------------------------------------------------------------------------------------------------------+ 1 row in set (0.00 sec) mysql> use tushanbu; mysql> show table status like 'tsb'G *************************** 1. row ***************************            Name: tsb          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: 2022-07-25 22:12:10     Update_time: NULL      Check_time: NULL       Collation: latin1_swedish_ci        Checksum: NULL  Create_options:          Comment:  1 row in set (0.00 sec) //进入数据库查看表的状态 

获取帮助

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,...) //获取创建表的帮助 

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 

mysql 基础
mysql 基础
mysql 基础

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。