数据结构模型主要有:
关系模型:
二维关系:row,column
数据库管理系统:DBMS
关系:Relational,RDBMS
常见的关系型数据库管理系统:
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
关系型数据库的常见组件有:
SQL语句有三种类型:
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 | xGRANT:授权 REVOKE:移除授权 |
mysql安装方式有三种:
#配置mysql的yum源
wget -O /usr/src/mysql57-community-release-el7-10.noarch.rpm \
http://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.rpm
rpm -Uvh /usr/src/mysql57-community-release-el7-10.noarch.rpm
#安装mysql5.7
yum -y install mysql-community-server mysql-community-client \
mysql-community-common mysql-community-devel
#启动mysql并设置开机自动启动
systemctl enable --now mysqld
systemctl status mysqld
#确保3306端口已经监听起来
ss -antl
#在日志文件中找出临时密码
grep "password" /var/log/mysqld.log
#使用获取到的临时密码登录mysql
[root@longnian ~]# 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 2
Server version: 5.7.23
Copyright (c) 2000, 2020, 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> //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 (0.01 sec)
mysql> ALTER USER 'root'@'localhost' IDENTIFIED BY 'longnian@123';
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
rpm -e mysql57-community-release
//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@longnian ~]# mysql -V
mysql Ver 14.14 Distrib 5.7.23, for Linux (x86_64) using EditLine wrapper
[root@longnian ~]# mysql -uroot -plongnian@123 -h192.168.159.135
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 4
Server version: 5.7.23 MySQL Community Server (GPL)
Copyright (c) 2000, 2020, 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>
//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 -p -h192.168.159.135
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 5
Server version: 5.7.23 MySQL Community Server (GPL)
Copyright (c) 2000, 2020, 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>
[root@localhost ~]# mysql -uroot -p -h 192.168.159.135 -e 'SHOW DATABASES;'
Enter password:
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| student |
+--------------------+
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 |
//创建数据库
//语法:CREATE DATABASE [IF NOT EXISTS] 'DB_NAME';
//创建数据库student
mysql> CREATE DATABASE IF NOT EXISTS student;
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 |
| student |
+--------------------+
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student
mysql> DROP DATABASE IF EXISTS student;
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wangqingge里创建表longnian
mysql> CREATE DATABASE student; //创建数据库student
Query OK, 1 row affected (0.00 sec)
mysql> use student; //进入student数据库
Database changed
mysql> CREATE TABLE longnian (id int NOT NULL,name VARCHAR(100) NOT NULL,age tinyint); //创建longnian表
Query OK, 0 rows affected (0.09 sec)
//查看当前数据库有哪些表
mysql> SHOW TABLES;
+----------------------+
| Tables_in_student |
+----------------------+
| longnian |
+----------------------+
1 row in set (0.00 sec)
//删除表
//语法:DROP TABLE [ IF EXISTS ] 'table_name';
//删除表longnian
mysql> DROP TABLE longnian;
Query OK, 0 rows affected (0.01 sec)
mysql> SHOW TABLES;
Empty set (0.00 sec)
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:
//数据库用户创建
//语法:CREATE USER 'username'@'host' [IDENTIFIED BY 'password'];
//创建数据库用户longnian
mysql> CREATE USER 'longnian'@'192.168.159.135' IDENTIFIED BY 'longnian@123';
Query OK, 0 rows affected (0.00 sec)
//使用新创建的用户和密码登录
[root@localhost ~]# mysql -ulongnian -plongnian@123 -h192.168.159.135
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, 2020, 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';
mysql> DROP USER 'longnian'@'192.168.159.135';
Query OK, 0 rows affected (0.00 sec)
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 |
| longnian |
+--------------------+
5 rows in set (0.00 sec)
mysql> SHOW TABLES FROM student; //不进入某数据库而列出其包含的所有表
+----------------------+
| Tables_in_student |
+----------------------+
| longnian |
+----------------------+
1 row in set (0.00 sec)
//查看表结构
//语法:DESC [db_name.]table_name;
mysql> DESC student.longnian;
+-------+--------------+------+-----+---------+-------+
| 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 TABLEstudent.longnian;
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+----------+-----------------------------------------------------------------------------------------------------------------------------------------------------------+
| wangqing | CREATE TABLE `longnian` (
`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 student; //进入数据库student
Database changed
mysql> SHOW TABLE STATUS LIKE 'longnian'\G //查看longnian表的状态
*************************** 1. row ***************************
Name: longnian
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: 2020-05-20 16:19:35
Update_time: NULL
Check_time: NULL
Collation: latin1_swedish_ci
Checksum: NULL
Create_options:
Comment:
1 row in set (0.00 sec)
//获取命令使用帮助
//语法:HELP keyword;
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
......
......
DML操作包括增(INSERT)、删(DELETE)、改(UPDATE)、查(SELECT),均属针对表的操作。
//DML操作之增操作insert
//语法:INSERT [INTO] table_name [(column_name,...)] {VALUES | VALUE} (value1,...),(...),...
mysql> use student;
Database changed
mysql> INSERT INTO longnian (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 longnian (id,name,age) VALUES (2,'jerry',23),(3,'longnian',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
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 vRLIKE: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 | 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 student;
Database changed
mysql> select * from longnian;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | xiaoming | 25 |
| 4 | xiaoai | 28 |
| 5 | xiaoli | 26 |
| 6 | xiaowang | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> SELECT name FROM longnian;
+-----------+
| name |
+-----------+
| tom |
| jerry |
| xiaoming |
| xiaoai |
| xiaoli |
| xiaowang |
| lisi |
+-----------+
7 rows in set (0.01 sec)
mysql> SELECT * FROM longnian ORDER BY age;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 7 | lisi | NULL |
| 1 | tom | 20 |
| 6 | xiaowang | 20 |
| 2 | jerry | 23 |
| 3 | xiaoming | 25 |
| 5 | xiaoli | 26 |
| 4 | xiaoai | 28 |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> SELECT * FROM longnian ORDER BY age DESC;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 4 | xiaoai | 28 |
| 5 | xiaoli | 26 |
| 3 | xiaoming | 25 |
| 2 | jerry | 23 |
| 1 | tom | 20 |
| 6 | xiaowang | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> SELECT * FROM longnian ORDER BY age limit 2;
+----+------+------+
| id | name | age |
+----+------+------+
| 7 | lisi | NULL |
| 1 | tom | 20 |
+----+------+------+
2 rows in set (0.00 sec)
mysql> SELECT * FROM longnian ORDER BY age limit 1,2;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 6 | xiaowang | 20 |
+----+-----------+------+
2 rows in set (0.00 sec)
mysql> SELECT * FROM longnian WHERE age >= 25;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 3 | xiaoming | 25 |
| 4 | xiaoai | 28 |
| 5 | xiaoli | 26 |
+----+-----------+------+
3 rows in set (0.00 sec)
mysql> SELECT * FROM longnian WHERE age >= 25 AND name = 'zhangshan';
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 5 | xiaoli | 26 |
+----+-----------+------+
1 row in set (0.00 sec)
mysql> SELECT * FROM longnian WHERE age BETWEEN 23 and 28;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 2 | jerry | 23 |
| 3 | xiaoming | 25 |
| 4 | xiaoai | 28 |
| 5 | xiaoli | 26 |
+----+-----------+------+
4 rows in set (0.00 sec)
mysql> select * from longnian where age is not null;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | xiaoming | 25 |
| 4 | xiaoai | 28 |
| 5 | xiaoli | 26 |
| 6 | xiaowang | 20 |
+----+-----------+------+
6 rows in set (0.00 sec)
mysql> select * from longnian where age is null;
+----+------+------+
| id | name | age |
+----+------+------+
| 7 | lisi | NULL |
+----+------+------+
1 row in set (0.00 sec)
//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 longnian;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | xiaoming | 25 |
| 4 | xiaoai | 28 |
| 5 | xiaoli | 26 |
| 6 | xiaowang | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> update longnian 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)
//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 longnian;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | xiaoming | 25 |
| 4 | xiaoai | 28 |
| 5 | xiaoli | 26 |
| 6 | xiaowang | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> delete from longnian where id = 7; //删除某条记录
Query OK, 1 row affected (0.00 sec)
mysql> select * from wangqing;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | xiaoming | 25 |
| 4 | xiaoai | 28 |
| 5 | xiaoli | 26 |
| 6 | xiaowang | 20 |
+----+-----------+------+
6 rows in set (0.00 sec)
mysql> delete from longnian; //删除整张表的内容
Query OK, 6 rows affected (0.00 sec)
mysql> select * from longnian;
Empty set (0.00 sec)
mysql> desc longnian;
+-------+--------------+------+-----+---------+-------+
| 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)
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 longnian;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | xiaoming | 25 |
| 4 | xiaoai | 28 |
| 5 | xiaoli | 26 |
| 6 | xiaowang | 20 |
| 7 | lisi | NULL |
+----+-----------+------+
7 rows in set (0.00 sec)
mysql> truncate longnian;
Query OK, 0 rows affected (0.01 sec)
mysql> select * from longnian;
Empty set (0.00 sec)
mysql> desc longnian;
+-------+--------------+------+-----+---------+-------+
| 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)
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 |
| student |
+--------------------+
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 'longnian'@'localhost' IDENTIFIED BY 'longnian@123';
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> GRANT ALL ON *.* TO 'longnian'@'192.168.159.135' IDENTIFIED BY 'longnian@123';
Query OK, 0 rows affected, 1 warning (0.00 sec)
//授权longnian用户在192.168.159.132上远程登录访问student数据库
mysql> GRANT ALL ON student.* TO 'wangqing'@'192.168.159.135' IDENTIFIED BY 'longnian@123';
Query OK, 0 rows affected, 1 warning (0.00 sec)
//授权longnian用户在所有位置上远程登录访问student数据库
mysql> GRANT ALL ON *.* TO 'longnian'@'%' IDENTIFIED BY 'longnian@123';
Query OK, 0 rows affected, 1 warning (0.00 sec)
//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longnian的授权信息
mysql> SHOW GRANTS FOR longnian;
+-----------------------------------------------+
| Grants for longnian@% |
+-----------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'longnian'@'%' |
+-----------------------------------------------+
1 row in set (0.00 sec)
mysql> SHOW GRANTS FOR 'longnian'@'localhost';
+-------------------------------------------------------+
| Grants for longnian@localhost |
+-------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'longnian'@'localhost' |
+-------------------------------------------------------+
1 row in set (0.00 sec)
mysql> SHOW GRANTS FOR 'longnian'@'192.168.159.135';
+-------------------------------------------------------+
| Grants for [email protected] |
+-------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'longnian'@'192.168.159.135' |
+-------------------------------------------------------+
1 row in set (0.00 sec)
//语法:REVOKE priv_type,... ON db_name.table_name FROM 'username'@'host';
mysql> REVOKE ALL ON *.* FROM 'longnian'@'192.168.159.132';
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:
mysql> FLUSH PRIVILEGES;
1.搭建mysql服务
[root@longnian ~]# systemctl stop firewalld.service 关闭防火墙
[root@longnian ~]# setenforce 0 关闭setLinux服务
[root@longnian ~]# cd /usr/src
[root@longnian src]# wget http://dev.mysql.com/get/mysql57-community-release-el7-10.noarch.rpm
[root@longnian src]# rpm -ivh mysql57-community-release-el7-10.noarch.rpm
[root@longnian src]# cd /etc/yum.repos.d
[root@longnian yum.repos.d]# yum -y install mysql-community-server mysql-community-client mysql-community-common mysql-community-devel
[root@longnian yum.repos.d]# systemctl start mysqld 启动mysqld服务
[root@longnian yum.repos.d]# systemctl status mysqld
[root@longnian yum.repos.d]# systemctl enable mysqld 开机启动
[root@longnian ~]# grep "password" /var/log/mysqld.log
2020-05-22T14:01:03.148212Z 1 [Note] A temporary password is generated for root@localhost: 1.*%ZQzys#/j
[root@longnian ~]# mysql -uroot -p1.*%ZQzys#/j
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 3
Server version: 5.7.30
Copyright (c) 2000, 2020, 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> 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 'longnian@123!';
Query OK, 0 rows affected (0.00 sec)
mysql> quit
Bye
2.创建一个以你名字为名的数据库,并创建一张表student,该表包含三个字段(id,name,age),表结构如下:
mysql> desc student;
+-------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(100) | NO | | NULL | |
| age | tinyint(4) | YES | | NULL | |
+-------+--------------+------+-----+---------+----------------+
3 rows in set (0.01 sec)
mysql> create database longnian;
Query OK, 1 row affected (0.00 sec)
mysql> use longnian
Database changed
mysql> create table student(id int(11) NOT NULL Key auto_increment,name CHAR(100) NOT NULL,age tinyint NULL);
Query OK, 0 rows affected (0.00 sec)
mysql> DESC longnian.student;
+-------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+--------------+------+-----+---------+----------------+
| id | int(11) | NO | PRI | NULL | auto_increment |
| name | varchar(100) | NO | | NULL | |
| age | tinyint(4) | YES | | NULL | |
+-------+--------------+------+-----+---------+----------------+
3 rows in set (0.01 sec)
3.查看下该新建的表有无内容(用select语句)
mysql> select * from student;
Empty set (0.00 sec)
4.往新建的student表中插入数据(用insert语句),结果应如下所示:
+----+-------------+------+
| id | name | age |
+----+-------------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
| 8 | chenshuo | 10 |
| 9 | wangwu | 3 |
| 10 | qiuyi | 15 |
| 11 | qiuxiaotian | 20 |
+----+-------------+------+
mysql> insert into student (id,name,age)values (1,'tom',20),(2,'jerry',23),(3,'wangqing',25),(4,'sean',28),(5,'zhangshan',26),(6,'zhangshan',20),(7,'lisi',NULL),(8,'chenshuo',10),(9,'wangwu',3),(10,'qiuyi',15),(11,'qiuxiaotian',20););
mysql> select * from student;
+----+-------------+------+
| id | name | age |
+----+-------------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | NULL |
| 8 | chenshuo | 10 |
| 9 | wangwu | 3 |
| 10 | qiuyi | 15 |
| 11 | qiuxiaotian | 20 |
+----+-------------+------+
11 rows in set (0.00 sec)
5.修改lisi的年龄为50
mysql> update student set age = 50 where name = 'lisi';
Query OK, 3 rows affected (0.00 sec)
Rows matched: 3 Changed: 3 Warnings: 0
mysql> select * from student;
+----+-------------+------+
| id | name | age |
+----+-------------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | 50 |
| 8 | chenshuo | 10 |
| 9 | wangwu | 3 |
| 10 | qiuyi | 15 |
| 11 | qiuxiaotian | 20 |
+----+-------------+------+
11 rows in set (0.00 sec)
6.以age字段降序排序
mysql> select * from student order by age desc;
+----+-------------+------+
| id | name | age |
+----+-------------+------+
| 7 | lisi | 50 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 3 | wangqing | 25 |
| 2 | jerry | 23 |
| 1 | tom | 20 |
| 6 | zhangshan | 20 |
| 11 | qiuxiaotian | 20 |
| 10 | qiuyi | 15 |
| 8 | chenshuo | 10 |
| 9 | wangwu | 3 |
+----+-------------+------+
11 rows in set (0.00 sec)
7.查询student表中年龄最小的3位同学跳过前2位
mysql> select * from student order by age limit 2,3;
+----+----------+------+
| id | name | age |
+----+----------+------+
| 6 | zhangshan | 20 |
| 10 | qiuyi | 15 |
| 11 | qiuxiaotian | 20 |
+----+----------+------+
3 rows in set (0.00 sec)
8.查询student表中年龄最大的4位同学
mysql> select * from student order by age desc limit 4;
+----+-----------+------+
| id | name | age |
+----+-----------+------+
| 7 | lisi | 50 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 3 | wangqing | 25 |
+----+-----------+------+
4 rows in set (0.00 sec)
9.查询student表中名字叫zhangshan的记录
mysql> select name from student where name='zhangshan';
+-----------+
| name |
+-----------+
| zhangshan |
| zhangshan |
+-----------+
2 rows in set (0.00 sec)
10.查询student表中名字叫zhangshan且年龄大于20岁的记录
mysql> select name from student where age>20 and name='zhangshan';
+-----------+
| name |
+-----------+
| zhangshan |
+-----------+
1 row in set (0.00 sec)
11.查询student表中年龄在23到30之间的记录
mysql> select name from student where age between 23 and 30 ;
+-----------+
| name |
+-----------+
| jerry |
| wangqing |
| sean |
| zhangshan |
+-----------+
4 rows in set (0.00 sec)
12.修改wangwu的年龄为100
mysql> update student set age = 100 where name = 'wangwu';
Query OK, 1 row affected (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from student;
+----+-------------+------+
| id | name | age |
+----+-------------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 6 | zhangshan | 20 |
| 7 | lisi | 50 |
| 8 | chenshuo | 10 |
| 9 | wangwu | 100 |
| 10 | qiuyi | 15 |
| 11 | qiuxiaotian | 20 |
+----+-------------+------+
11 rows in set (0.00 sec)
13.删除student中名字叫zhangshan且年龄小于等于20的记录
mysql> delete from student where name='zhangshan' and age <= 20;
Query OK, 1 row affected (0.00 sec)
mysql> select * from student;
+----+-------------+------+
| id | name | age |
+----+-------------+------+
| 1 | tom | 20 |
| 2 | jerry | 23 |
| 3 | wangqing | 25 |
| 4 | sean | 28 |
| 5 | zhangshan | 26 |
| 7 | lisi | 50 |
| 8 | chenshuo | 10 |
| 9 | wangwu | 100 |
| 10 | qiuyi | 15 |
| 11 | qiuxiaotian | 20 |
+----+-------------+------+
10 rows in set (0.00 sec)