MySQL SQL语句

Strong 2021年02月28日 1,214次浏览

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
DDLCREATE:创建
DROP:删除
ALTER:修改
DMLINSERT: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
DCLGRANT: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hzz
mysql> CREATE DATABASE IF NOT EXISTS hzz;
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                |
| hzz	             |
+--------------------+
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hzz
mysql> DROP DATABASE IF EXISTS hzz;
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)

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hzz里创建表hzztable
mysql> CREATE DATABASE hzz;      	//创建数据库hzz
Query OK, 1 row affected (0.00 sec)

mysql> use hzz;      			//进入hzz数据库
Database changed

//创建hzztable表
mysql> CREATE TABLE hzztable (id int 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_hzz |
+----------------------+
| hzztable             |
+----------------------+
1 row in set (0.00 sec)

//删除表
//语法:DROP TABLE [ IF EXISTS ] 'table_name';

//删除表hzztable
mysql> DROP TABLE hzztable;
Query OK, 0 rows affected (0.01 sec)

mysql> SHOW TABLES;
Empty set (0.00 sec)

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: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hzz
mysql> CREATE USER 'hzz'@'127.0.0.1' IDENTIFIED BY 'hzz123!';
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 -uhzz -phzz123! -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hzz
mysql> DROP USER 'hzz'@'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 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                |
| hzz                |
+--------------------+
5 rows in set (0.00 sec)

mysql> SHOW TABLES FROM hzz;         	//不进入某数据库而列出其包含的所有表
+----------------------+
| Tables_in_hzz        |
+----------------------+
| hzztable             |
+----------------------+
1 row in set (0.00 sec)

//查看表结构
//语法:DESC [db_name.]table_name;

mysql> DESC hzz.hzztable;
+-------+--------------+------+-----+---------+-------+
| 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 hzz.hzztable;
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table    | Create Table                                                                                                                                              |
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| hzztable | CREATE TABLE `hzz` (
  `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 hzz;      //进入数据库hzz
Database changed
mysql> SHOW TABLE STATUS LIKE 'hzztable'\G      //查看hzztable表的状态
*************************** 1. row ***************************
           Name: hzztable
         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 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
 ......
 ......

1.6 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 hzz CHARACTER SET utf8;
Query OK, 1 row affected (0.000 sec)

//修改表
//语法:ALTER TABLE <table_name> [option]

//给hzztable表添加新的一列,先查看表结构
mysql> DESC hzztable;
+-------+-------------+------+-----+---------+-------+
| 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hzztable表添加一列'phone'
mysql> ALTER TABLE hzztable 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 hzztable;
+-------+-------------+------+-----+---------+-------+
| 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hzztable表中'phone'列为'sex'
mysql> ALTER TABLE hzztable CHANGE phone sex varchar(4);
Query OK, 0 rows affected (0.005 sec)              
Records: 0  Duplicates: 0  Warnings: 0

mysql> DESC hzztable;
+-------+-------------+------+-----+---------+-------+
| 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zzhtable
mysql> ALTER TABLE hzztable RENAME TO zzhtable;
Query OK, 0 rows affected (0.002 sec)

mysql> SHOW TABLES;
+---------------+
| Tables_in_hzz |
+---------------+
| zzhtable      |
+---------------+
1 row in set (0.000 sec)

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 hzz;
Database changed

//一次插入一条记录
mysql> INSERT INTO hzztable (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 hzztable (id,name,age) VALUES (2,'jerry',23),(3,'hzz',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 hzz;
Database changed

mysql> select * from hzztable;
+----+-----------+------+
| id | name      | age  |
+----+-----------+------+
|  1 | tom       |   20 |
|  2 | jerry     |   23 |
|  3 | hzz       |   25 |
|  4 | sean      |   28 |
|  5 | zhangshan |   26 |
|  6 | zhangshan |   20 |
|  7 | lisi      | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)

mysql> SELECT name FROM hzztable;
+-----------+
| name      |
+-----------+
| tom       |
| jerry     |
| hzz       |
| sean      |
| zhangshan |
| zhangshan |
| lisi      |
+-----------+
7 rows in set (0.01 sec)

mysql> SELECT * FROM hzztable ORDER BY age;
+----+-----------+------+
| id | name      | age  |
+----+-----------+------+
|  7 | lisi      | NULL |
|  1 | tom       |   20 |
|  6 | zhangshan |   20 |
|  2 | jerry     |   23 |
|  3 | hzz       |   25 |
|  5 | zhangshan |   26 |
|  4 | sean      |   28 |
+----+-----------+------+
7 rows in set (0.00 sec)

mysql> SELECT * FROM hzztable ORDER BY age DESC;
+----+-----------+------+
| id | name      | age  |
+----+-----------+------+
|  4 | sean      |   28 |
|  5 | zhangshan |   26 |
|  3 | hzz       |   25 |
|  2 | jerry     |   23 |
|  1 | tom       |   20 |
|  6 | zhangshan |   20 |
|  7 | lisi      | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)

mysql> SELECT * FROM hzztable ORDER BY age limit 2;
+----+------+------+
| id | name | age  |
+----+------+------+
|  7 | lisi | NULL |
|  1 | tom  |   20 |
+----+------+------+
2 rows in set (0.00 sec)

mysql> SELECT * FROM hzztable 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 hzztable WHERE age >= 25;
+----+-----------+------+
| id | name      | age  |
+----+-----------+------+
|  3 | hzz       |   25 |
|  4 | sean      |   28 |
|  5 | zhangshan |   26 |
+----+-----------+------+
3 rows in set (0.00 sec)

mysql> SELECT * FROM hzztable WHERE age >= 25 AND name = 'zhangshan';
+----+-----------+------+
| id | name      | age  |
+----+-----------+------+
|  5 | zhangshan |   26 |
+----+-----------+------+
1 row in set (0.00 sec)

mysql> SELECT * FROM hzztable WHERE age BETWEEN 23 and 28;
+----+-----------+------+
| id | name      | age  |
+----+-----------+------+
|  2 | jerry     |   23 |
|  3 | hzz       |   25 |
|  4 | sean      |   28 |
|  5 | zhangshan |   26 |
+----+-----------+------+
4 rows in set (0.00 sec)

mysql> select * from hzztable where age is not null;
+----+-----------+------+
| id | name      | age  |
+----+-----------+------+
|  1 | tom       |   20 |
|  2 | jerry     |   23 |
|  3 | hzz       |   25 |
|  4 | sean      |   28 |
|  5 | zhangshan |   26 |
|  6 | zhangshan |   20 |
+----+-----------+------+
6 rows in set (0.00 sec)

mysql> select * from hzztable 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 hzztable;
+----+-----------+------+
| id | name      | age  |
+----+-----------+------+
|  1 | tom       |   20 |
|  2 | jerry     |   23 |
|  3 | hzz       |   25 |
|  4 | sean      |   28 |
|  5 | zhangshan |   26 |
|  6 | zhangshan |   20 |
|  7 | lisi      | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)

mysql> update hzztable set age = 30 where name = 'lisi';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select * from hzztable 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 hzztable;
+----+-----------+------+
| id | name      | age  |
+----+-----------+------+
|  1 | tom       |   20 |
|  2 | jerry     |   23 |
|  3 | hzz       |   25 |
|  4 | sean      |   28 |
|  5 | zhangshan |   26 |
|  6 | zhangshan |   20 |
|  7 | lisi      |   30 |
+----+-----------+------+
7 rows in set (0.00 sec)

mysql> delete from hzztable where id = 7;       //删除某条记录
Query OK, 1 row affected (0.00 sec)

mysql> select * from hzztable;
+----+-----------+------+
| id | name      | age  |
+----+-----------+------+
|  1 | tom       |   20 |
|  2 | jerry     |   23 |
|  3 | hzz       |   25 |
|  4 | sean      |   28 |
|  5 | zhangshan |   26 |
|  6 | zhangshan |   20 |
+----+-----------+------+
6 rows in set (0.00 sec)

mysql> delete from hzztable;        //删除整张表的内容
Query OK, 6 rows affected (0.00 sec)

mysql> select * from hzztable;
Empty set (0.00 sec)

mysql> desc hzztable;
+-------+--------------+------+-----+---------+-------+
| 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
deleteDELETE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 hzztable;
+----+-----------+------+
| id | name      | age  |
+----+-----------+------+
|  1 | tom       |   20 |
|  2 | jerry     |   23 |
|  3 | hzz       |   25 |
|  4 | sean      |   28 |
|  5 | zhangshan |   26 |
|  6 | zhangshan |   20 |
|  7 | lisi      | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)

mysql> truncate hzztable;
Query OK, 0 rows affected (0.01 sec)

mysql> select * from hzztable;
Empty set (0.00 sec)

mysql> desc hzztable;
+-------+--------------+------+-----+---------+-------+
| 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                |
| hzz                |
+--------------------+
5 rows in set (0.00 sec)

//授权hzz用户在数据库本机上登录访问所有数据库
mysql> GRANT ALL ON *.* TO 'hzz'@'localhost' IDENTIFIED BY 'hzz123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)

//也可表示为:
mysql> GRANT ALL ON *.* TO 'hzz'@'127.0.0.1' IDENTIFIED BY 'hzz123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)

//授权hzz用户在172.16.12.129上远程登录访问hzz数据库
mysql> GRANT ALL ON hzz.* TO 'hzz'@'172.16.12.129' IDENTIFIED BY 'hzz123!';
Query OK, 0 rows affected, 1 warning (0.00 sec)

//授权hzz用户在所有位置上远程登录访问hzz数据库
mysql> GRANT ALL ON hzz.* TO 'hzz'@'%' IDENTIFIED BY 'hzz123!';
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hzz的授权信息
mysql> SHOW GRANTS FOR 'hzz'@'localhost';
+-------------------------------------------------------+
| Grants for hzz@localhost                              |
+-------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'hzz'@'localhost'      |
+-------------------------------------------------------+
1 row in set (0.00 sec)

mysql> SHOW GRANTS FOR 'hzz'@'127.0.0.1';
+-------------------------------------------------------+
| Grants for hzz@127.0.0.1                              |
+-------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'hzz'@'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 'hzz'@'172.16.12.129';
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;