1、创建数据库 mysql> create database martin; Query OK, 1 row affected (0.05 sec) mysql> show create database martin\G; *************************** 1. row *************************** Database: martin Create Database: CREATE DATABASE `martin` /*!40100 DEFAULT CHARACTER SET latin1 */ 1 row in set (0.00 sec) mysql> create database martin_gbk DEFAULT CHARACTER SET gbk COLLATE gbk_chinese_ci; #gbk 代表字符集 gbk_chinese_ci代表校对规则 Query OK, 1 row affected (0.00 sec) mysql> show create database martin_gbk\G; *************************** 1. row *************************** Database: martin_gbk Create Database: CREATE DATABASE `martin_gbk` /*!40100 DEFAULT CHARACTER SET gbk */ 1 row in set (0.00 sec) mysql> create database martin_utf8 DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci; #utf8 编码，字符集的不一致时数据库乱码的罪魁祸首 Query OK, 1 row affected (0.00 sec) mysql> show create database martin_utf8\G; *************************** 1. row *************************** Database: martin_utf8 Create Database: CREATE DATABASE `martin_utf8` /*!40100 DEFAULT CHARACTER SET utf8 */ 1 row in set (0.00 sec) 编译时候指定了特定的字符集，则以后创建的数据库就不需要指定字符集了 企业环境怎么创建数据库 1、根据开发的程序确定字符集 建议utf8 2、编译时候指定字符集 3、然后建库的时候默认创建即可 显示数据库 mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | martin | | martin_gbk | | martin_utf8 | | mysql | | performance_schema | | test | +--------------------+ 7 rows in set (0.21 sec) mysql> show databases like ‘mar%‘; +-----------------+ | Database (mar%) | +-----------------+ | martin | | martin_gbk | | martin_utf8 | +-----------------+ 3 rows in set (0.00 sec) 删除数据库 mysql> drop database martin; Query OK, 0 rows affected (0.27 sec) 连接数据库 mysql> use mysql; Database changed 查看当前连接的数据库 mysql> select database(); +------------+ | database() | +------------+ | mysql | +------------+ 1 row in set (0.00 sec) 查看当前的用户 mysql> select user(); +----------------+ | user() | +----------------+ | [email protected] | +----------------+ 1 row in set (0.00 sec) 查看当前数据库包含的表信息 mysql> show tables; +---------------------------+ | Tables_in_mysql | +---------------------------+ | columns_priv | | db | | event | | func | | general_log | | help_category | | help_keyword | | help_relation | | help_topic | | host | | ndb_binlog_index | | plugin | | proc | | procs_priv | | proxies_priv | | servers | | slow_log | | tables_priv | | time_zone | | time_zone_leap_second | | time_zone_name | | time_zone_transition | | time_zone_transition_type | | user | +---------------------------+ 24 rows in set (0.03 sec) 删除用户 语法： drop user ‘user‘@‘主机名‘ mysql> select user,host from mysql.user; +--------+-----------+ | user | host | +--------+-----------+ | root | 127.0.0.1 | | root | ::1 | | root | centos02 | | root | localhost | | system | localhost | +--------+-----------+ 5 rows in set (0.00 sec) mysql> drop user ‘root‘@‘::1‘; Query OK, 0 rows affected (0.05 sec) mysql> select user,host from mysql.user; +--------+-----------+ | user | host | +--------+-----------+ | root | 127.0.0.1 | | root | centos02 | | root | localhost | | system | localhost | +--------+-----------+ 4 rows in set (0.00 sec) 创建mysql用户及赋予用户权限 mysql> grant all on martin.* to [email protected]‘localhost‘ identified by ‘123456‘; #在创建用户时候同时进行授权 Query OK, 0 rows affected (0.05 sec) mysql> select user,host from mysql.user; +--------+-----------+ | user | host | +--------+-----------+ | root | 127.0.0.1 | | root | centos02 | | root | localhost | | system | localhost | | zabbix | localhost | +--------+-----------+ 5 rows in set (0.00 sec) mysql> show grants for [email protected]‘localhost‘; +---------------------------------------------------------------------------------------------------------------+ | Grants for [email protected] | +---------------------------------------------------------------------------------------------------------------+ | GRANT USAGE ON *.* TO ‘zabbix‘@‘localhost‘ IDENTIFIED BY PASSWORD ‘*6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9‘ | | GRANT ALL PRIVILEGES ON `martin`.* TO ‘zabbix‘@‘localhost‘ | +---------------------------------------------------------------------------------------------------------------+ 2 rows in set (0.00 sec) mysql> grant all on martin.* to [email protected]‘localhost‘ identified by ‘123456‘; #在创建用户时候同时进行授权 等同于下面两句话 mysql> create user [email protected]‘localhost‘ identified by ‘123456‘; 创建用户及设置用户密码 grant all on zabbix.* [email protected]‘localhost‘; 授权 mysql> create user [email protected]‘localhost‘ identified by ‘123456‘; 创建用户不进行授权，默认是USAGE 权限 Query OK, 0 rows affected (0.00 sec) mysql> mysql> mysql> show grants for [email protected]‘localhost‘; +------------------------------------------------------------------------------------------------------------------+ | Grants for [email protected] | +------------------------------------------------------------------------------------------------------------------+ | GRANT USAGE ON *.* TO ‘martin123‘@‘localhost‘ IDENTIFIED BY PASSWORD ‘*6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9‘ | +------------------------------------------------------------------------------------------------------------------+ 1 row in set (0.00 sec) 授权局域网内主机远程连接数据库 mysql> grant all on martin.* to [email protected]‘172.16.80.%‘ identified by ‘123456‘; 通过实验获得 all privilege 到底有哪些权限 mysql> show grants for [email protected]‘localhost‘; +---------------------------------------------------------------------------------------------------------------+ | Grants for [email protected] | +---------------------------------------------------------------------------------------------------------------+ | GRANT USAGE ON *.* TO ‘zabbix‘@‘localhost‘ IDENTIFIED BY PASSWORD ‘*6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9‘ | | GRANT ALL PRIVILEGES ON `martin`.* TO ‘zabbix‘@‘localhost‘ | +---------------------------------------------------------------------------------------------------------------+ 2 rows in set (0.00 sec) mysql> revoke insert on martin.* from ‘zabbix‘@‘localhost‘; #回收insert权限 Query OK, 0 rows affected (0.01 sec) mysql> show grants for [email protected]‘localhost‘; +----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | Grants for [email protected] | +----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ | GRANT USAGE ON *.* TO ‘zabbix‘@‘localhost‘ IDENTIFIED BY PASSWORD ‘*6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9‘ | | GRANT SELECT, UPDATE, DELETE, CREATE, DROP, REFERENCES, INDEX, ALTER, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, EVENT, TRIGGER ON `martin`.* TO ‘zabbix‘@‘localhost‘ | +----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+ 2 rows in set (0.00 sec) 可以看到剩下的权限有 SELECT, UPDATE, DELETE, CREATE, DROP, REFERENCES, INDEX, ALTER, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, EVENT, TRIGGER mysql> select * from mysql.user\G; *************************** 1. row *************************** Host: localhost User: root Password: *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 Select_priv: Y Insert_priv: Y Update_priv: Y Delete_priv: Y Create_priv: Y Drop_priv: Y Reload_priv: Y 企业生产环境如何授权用户权限 1、博客 cms等产品的数据库授权： 对于web连接用户授权尽量采用最小化原则，很多开源软件都是web界面安装，因此在安全期间除了 select insert update delete 4个权限外，还需要create drop 等比较危险的权限 mysql> grant select,insert,update,delete,create,drop on blog.* to [email protected]‘172.16.80.%‘ identified by ‘123456‘; 2、生成数据库表后，要回收create drop授权 revoke create on blog.* from blog @‘172.16.80.%‘; revoke drop on blog.* from blog @‘172.16.80.%‘; 创建表语法 create table 表名 (字段名1 类型1，字段名n，类型n); mysql> create table student(id int(4) not null,name char(20) not null, age tinyint(20) not null default 0,dept varchar(16) default null); Query OK, 0 rows affected (0.21 sec) 查看建表的结构 mysql> desc student; +-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | id | int(4) | NO | | NULL | | | name | char(20) | NO | | NULL | | | age | tinyint(20) | NO | | 0 | | | dept | varchar(16) | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 4 rows in set (0.03 sec) 查看已建表的语句 mysql> show create table student \G; *************************** 1. row *************************** Table: student Create Table: CREATE TABLE `student` ( `id` int(4) NOT NULL, `name` char(20) NOT NULL, `age` tinyint(20) NOT NULL DEFAULT ‘0‘, `dept` varchar(16) DEFAULT NULL ) ENGINE=InnoDB DEFAULT CHARSET=latin1 1 row in set (0.03 sec) 为表的字段创建索引 索引就像书的目录一样，如果在字段上建立了索引，那么以索引列为查询条件时可以加快查询速度，这是mysql优化的重要内容之一 建立主键索引 mysql> create table student1(id int(4) not null AUTO_INCREMENT, name char(20) not null, age tinyint(20) not null default 0,dept varchar(16) default null, primary key(id), key index_name(name) ); primary key(id) 表示主键 key index_name(name) name字段普通索引 mysql> desc student1; +-------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+----------------+ | id | int(4) | NO | PRI | NULL | auto_increment | | name | char(20) | NO | MUL | NULL | | | age | tinyint(20) | NO | | 0 | | | dept | varchar(16) | YES | | NULL | | +-------+-------------+------+-----+---------+----------------+ 4 rows in set (0.00 sec) 利用alter命令修改id列为自增主键列 （一般在建表的时候就该创建主键，所以一般不这样使用） mysql> desc student; +-------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+-------+ | id | int(4) | NO | | NULL | | | name | char(20) | NO | | NULL | | | age | tinyint(20) | NO | | 0 | | | dept | varchar(16) | YES | | NULL | | +-------+-------------+------+-----+---------+-------+ 4 rows in set (0.00 sec) mysql> mysql> mysql> alter table student change id id int primary key auto_increment; Query OK, 0 rows affected (0.22 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc student; +-------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | char(20) | NO | | NULL | | | age | tinyint(20) | NO | | 0 | | | dept | varchar(16) | YES | | NULL | | +-------+-------------+------+-----+---------+----------------+ 4 rows in set (0.00 sec) 增加索引 mysql> alter table student add index index_name(name); Query OK, 0 rows affected (1.63 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc student; +-------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | char(20) | NO | MUL | NULL | | | age | tinyint(20) | NO | | 0 | | | dept | varchar(16) | YES | | NULL | | +-------+-------------+------+-----+---------+----------------+ 4 rows in set (0.00 sec) 删除索引 mysql> alter table student drop index index_name; Query OK, 0 rows affected (0.06 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> desc student; +-------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------+-------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | char(20) | NO | | NULL | | | age | tinyint(20) | NO | | 0 | | | dept | varchar(16) | YES | | NULL | | +-------+-------------+------+-----+---------+----------------+ 4 rows in set (0.00 sec) 问题1：既然索引可以加快查询速度，那么给所有的列建索引吧？ 解答：因为索引不但占用系统空间，更新数据库时还需要维护索引数据的，因此，索引是一把双刃剑，并不是越多越好 问题2：需要在哪些列上创建索引？ 解答：select user,host from mysql.user where host=... 索引一定要创建在where后的条件列上，而不是select后的选择数据的列
时间： 2024-10-25 09:24:14