MySQL SQL语句
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 |
1、DDL操作
1.1 数据库DDL操作
//创建数据库
//语法：CREATE DATABASE [IF NOT EXISTS] 'DB_NAME';
//创建数据库hhr
mysql> CREATE DATABASE IF NOT EXISTS hhr;
Query OK, 1 row affected (0.00 sec)
//查看当前实例有哪些数据库
mysql> SHOW DATABASES;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| hhr |
+--------------------+
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hhr
mysql> DROP DATABASE IF EXISTS hhr;
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)
//创建数据库时,设置数据库的编码方式：
//CHARACTER SET:指定数据库采用的字符集,utf8不能写成utf-8
//COLLATE:指定数据库字符集的排序规则,utf8的默认排序规则为utf8_general_ci（通过show character set查看）
mysql> CREATE DATABASE dbtest CHARACTER SET utf8 COLLATE utf8_general_ci;
1.2 表DDL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hhr里创建表hhrtable
mysql> CREATE DATABASE hhr; //创建数据库hhr
Query OK, 1 row affected (0.00 sec)
mysql> use hhr; //进入hhr数据库
Database changed
//创建hhrtable表
mysql> CREATE TABLE hhrtable (id int(10) NOT NULL,name VARCHAR(100) NOT NULL,age tinyint);
Query OK, 0 rows affected (0.09 sec)
//查看当前数据库有哪些表
mysql> SHOW TABLES;
+----------------------+
| Tables_in_hhr |
+----------------------+
| hhrtable |
+----------------------+
1 row in set (0.00 sec)
//删除表
//语法：DROP TABLE [ IF EXISTS ] 'table_name';
//删除表hhrtable
mysql> DROP TABLE hhrtable;
Query OK, 0 rows affected (0.01 sec)
mysql> SHOW TABLES;
Empty set (0.00 sec)
//创建表时，设置字段、表的字符编码
mysql> CREATE TABLE tbtest(id int(10),user_name varchar(60) CHARACTER SET GBK COLLATE gbk_chinese_ci,email varchar(60))CHARACTER SET utf8 COLLATE utf8_general_ci;
1.3 用户DDL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；HOST用于限制此用户可通过哪些主机远程连接mysql程序。
HOST的值可为：
- IP地址，如：192.168.129.33
- 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hhr
mysql> CREATE USER 'hhr'@'127.0.0.1' IDENTIFIED BY 'hhr123!';
Query OK, 0 rows affected (0.00 sec)
//刷新授权表
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.006 sec)
//使用新创建的用户和密码登录
[root@localhost ~]# mysql -uhhr -phhr123! -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hhr
mysql> DROP USER 'hhr'@'127.0.0.1';
Query OK, 0 rows affected (0.00 sec)
//刷新授权表
mysql> FLUSH PRIVILEGES;
Query OK, 0 rows affected (0.006 sec)
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 |
......
......
mysql> SHOW VARIABLES LIKE '%char%'; //查看数据库的字符编码
.....
.....
mysql> SELECT CHARSET(email) FROM tbtest; //查看某表中某字段使用的字符编码
.....
.....
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 |
| sys |
| hhr |
+--------------------+
5 rows in set (0.00 sec)
mysql> SHOW TABLES FROM hhr; //不进入某数据库而列出其包含的所有表
+----------------------+
| Tables_in_hhr |
+----------------------+
| hhrtable |
+----------------------+
1 row in set (0.00 sec)
//查看表结构
//语法：DESC [db_name.]table_name;
mysql> DESC hhr.hhrtable;
+-------+--------------+------+-----+---------+-------+
| 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，可以看到创建表时设置的参数
//语法：SHOW CREATE TABLE table_name;
mysql> SHOW CREATE TABLE hhr.hhrtable;
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| hhrtable | CREATE TABLE `hhr` (
`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> use hhr; //进入数据库hhr
Database changed
mysql> SHOW TABLE STATUS LIKE 'hhrtable'\G //查看hhrtable表的状态
*************************** 1. row ***************************
Name: hhrtable
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)
1.5 ALTER修改操作
//修改数据库属性
//语法：ALTER DATABASE 'DB_NAME' CHARACTER SET charset_name | COLLATE collation_name
//修改数据库字符集为utf8
mysql> ALTER DATABASE hhr CHARACTER SET utf8;
Query OK, 1 row affected (0.000 sec)
//修改表
//语法：ALTER TABLE <table_name> [option]
//给hhrtable表添加新的一列，先查看表结构
mysql> DESC hhrtable;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id | int(7) | NO | | NULL | |
| name | varchar(20) | NO | | NULL | |
| age | tinyint(4) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+
3 rows in set (0.001 sec)
//给hhrtable表添加一列'phone'
mysql> ALTER TABLE hhrtable ADD phone int(11);
Query OK, 0 rows affected (0.001 sec)
Records: 0 Duplicates: 0 Warnings: 0
//查看表结构
mysql> DESC hhrtable;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id | int(7) | NO | | NULL | |
| name | varchar(20) | NO | | NULL | |
| age | tinyint(4) | YES | | NULL | |
| phone | int(11) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+
4 rows in set (0.000 sec)
//修改hhrtable表中'phone'列为'sex'
mysql> ALTER TABLE hhrtable CHANGE phone sex varchar(4);
Query OK, 0 rows affected (0.005 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> DESC hhrtable;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id | int(7) | NO | | NULL | |
| name | varchar(20) | NO | | NULL | |
| age | tinyint(4) | YES | | NULL | |
| sex | varchar(4) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+
4 rows in set (0.001 sec)
//修改表名为rhhtable
mysql> ALTER TABLE hhrtable RENAME TO rhhtable;
Query OK, 0 rows affected (0.002 sec)
mysql> SHOW TABLES;
+---------------+
| Tables_in_hhr |
+---------------+
| rhhtable |
+---------------+
1 row in set (0.000 sec)
//修改数据库字符编码
mysql> ALTER DATABASE dbtest CHARACTER SET utf8 COLLATE utf8_general_ci;
//修改表字符编码
mysql> ALTER TABLE tbtest CHARACTER SET utf8 COLLATE utf8_general_ci;
1.6 获取帮助
//获取命令使用帮助
//语法：HELP commond;
mysql> HELP CREATE TABLE; //获取创建表的帮助
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
......
......
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。
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 hhr;
Database changed
//一次插入一条记录
mysql> INSERT INTO hhrtable (id,name,age) VALUE (1,'tom',20);
Query OK, 1 row affected (0.01 sec)
//一次插入多条记录
mysql> INSERT INTO hhrtable (id,name,age) VALUES (2,'jerry',23),(3,'hhr',25),(4,'sean',28),(5,'zhangshan',26),(6,'zhangshan',20),(7,'lisi',NULL);
Query OK, 4 rows affected (0.01 sec)
Records: 4 Duplicates: 0 Warnings: 0
2.2 SELECT语句
字段column表示法:
| 表示符 | 含义 |
|---|---|
| * | 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 | AND OR NOT |
ORDER BY：排序，默认为升序（ASC）:
| ORDER BY语句 | 含义 |
|---|---|
| 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 hhr;
Database changed
mysql> select * from hhrtable;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | hhr | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> SELECT name FROM hhrtable;
+-----------+
| name |
+-----------+
| tom |
| jerry |
| hhr |
| sean |
| zhangshan |
| zhangshan |
| lisi |
+-----------+
7 rows in set (0.01 sec)
mysql> SELECT * FROM hhrtable ORDER BY age;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 7 | lisi | NULL |
| 1 | tom | 20 |
| 6 | zhangshan | 20 |
| 2 | jerry | 23 |
| 3 | hhr | 25 |
| 5 | zhangshan | 26 |
| 4 | sean | 28 |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> SELECT * FROM hhrtable ORDER BY age DESC;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 3 | hhr | 25 |
| 2 | jerry | 23 |
| 1 | tom | 20 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> SELECT * FROM hhrtable ORDER BY age limit 2;
+----+------+------+
| id | name | age |
+----+------+------+
| 7 | lisi | NULL |
| 1 | tom | 20 |
+----+------+------+
2 rows in set (0.00 sec)
mysql> SELECT * FROM hhrtable 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 hhrtable WHERE age >= 25;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 3 | hhr | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
+----+-----------+------+
3 rows in set (0.00 sec)
mysql> SELECT * FROM hhrtable WHERE age >= 25 AND name = 'zhangshan';
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 5 | zhangshan | 26 |
+----+-----------+------+
1 row in set (0.00 sec)
mysql> SELECT * FROM hhrtable WHERE age BETWEEN 23 and 28;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 2 | jerry | 23 |
| 3 | hhr | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
+----+-----------+------+
4 rows in set (0.00 sec)
mysql> select * from hhrtable where age is not null;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | hhr | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
+----+-----------+------+
6 rows in set (0.00 sec)
mysql> select * from hhrtable where age is null;
+----+------+------+
| id | name | age |
+----+------+------+
| 7 | lisi | NULL |
+----+------+------+
1 row in set (0.00 sec)
2.2 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 hhrtable;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | hhr | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> update hhrtable set age = 30 where name = 'lisi';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from hhrtable where name = 'lisi';
+----+------+------+
| id | name | age |
+----+------+------+
| 7 | lisi | 30 |
+----+------+------+
1 row in set (0.00 sec)
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 hhrtable;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | hhr | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | 30 |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> delete from hhrtable where id = 7; //删除某条记录
Query OK, 1 row affected (0.00 sec)
mysql> select * from hhrtable;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | hhr | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
+----+-----------+------+
6 rows in set (0.00 sec)
mysql> delete from hhrtable; //删除整张表的内容
Query OK, 6 rows affected (0.00 sec)
mysql> select * from hhrtable;
Empty set (0.00 sec)
mysql> desc hhrtable;
+-------+--------------+------+-----+---------+-------+
| 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)
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 hhrtable;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | hhr | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> truncate hhrtable;
Query OK, 0 rows affected (0.01 sec)
mysql> select * from hhrtable;
Empty set (0.00 sec)
mysql> desc hhrtable;
+-------+--------------+------+-----+---------+-------+
| 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)
3、DCL操作
3.1 创建授权grant
权限类型(priv_type)
| 权限类型 | 含义 |
|---|---|
| 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 | 含义 |
|---|---|
| . | 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。
//语法：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 |
| hhr |
+--------------------+
5 rows in set (0.00 sec)
//授权hhr用户在数据库本机上登录访问所有数据库
mysql> GRANT ALL ON *.* TO 'hhr'@'localhost' IDENTIFIED BY 'hhr123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)
//也可表示为：
mysql> GRANT ALL ON *.* TO 'hhr'@'127.0.0.1' IDENTIFIED BY 'hhr123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)
//授权hhr用户在192.168.129.33上远程登录访问hhr数据库
mysql> GRANT ALL ON hhr.* TO 'hhr'@'192.168.129.33' IDENTIFIED BY 'hhr123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)
//授权hhr用户在所有位置上远程登录访问hhr数据库
mysql> GRANT ALL ON hhr.* TO 'hhr'@'%' IDENTIFIED BY 'hhr123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)
//刷新授权表
mysql> FLUSH PRIVILEGES;
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hhr的授权信息
mysql> SHOW GRANTS FORM 'hhr'@'localhost';
+-------------------------------------------------------+
| Grants for hhr@localhost |
+-------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'hhr'@'localhost' |
+-------------------------------------------------------+
1 row in set (0.00 sec)
mysql> SHOW GRANTS FORM 'hhr'@'127.0.0.1';
+-------------------------------------------------------+
| Grants for hhr@127.0.0.1 |
+-------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'hhr'@'127.0.0.1' |
+-------------------------------------------------------+
1 row in set (0.00 sec)
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 'hhr'@'192.168.129.33';
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;
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