Advanced MySQL database management

One, the basic operation of the database

1.1 View the database structure-1

■ View database information

SHOW   DATABASES

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| auth               |
| myadm              |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
6 rows in set (0.00 sec)

1.2 View database structure-2

■ View table information in the database

USE 数据库名

mysql> use mysql;
Database changed
mysql> show tables;
+---------------------------+
| Tables_in_mysql           |
+---------------------------+
| columns_priv              |
| db                        |
| engine_cost               |
| event                     |
| func                      |
| general_log               |
| gtid_executed             |
| help_category             |
| help_keyword              |
......
31 rows in set (0.00 sec)

1.3 View the database structure -3

■ Display the structure (fields) of the data table

DESCRIBE [数据库名.]表名

###也可以使用“desc user;”
mysql> describe user;
+------------------------+-----------------------------------+------+-----+-----------------------+-------+
| Field                  | Type                              | Null | Key | Default               | Extra |
+------------------------+-----------------------------------+------+-----+-----------------------+-------+
| Host                   | char(60)                          | NO   | PRI |                       |       |
| User                   | char(32)                          | NO   | PRI |                       |       |
| Select_priv            | enum('N','Y')                     | NO   |     | N                     |       |
......

Two, create and manage databases and tables

2.1 Create database and table

■ DDL statements can be used to create database objects, such as libraries, tables, indexes, etc.
■ Use DDL statements to create new libraries and tables

• Create database CREATE DATABASE 数据库名
• Create data tableCREATE TABLE 表名（字段定义......）

mysql> create database auth;
Query OK, 1 row affected (0.00 sec)
mysql> use auth;
Database changed
mysql> 
mysql> create table users (user_name CHAR(16) NOT NULL,user_passwd CHAR(48) DEFAULT'',PRIMARY KEY (user_name));
Query OK, 0 rows affected (0.01 sec)

2.2 Data in the management table-1

■ DML statement is used to manage the data in the table
■ Include operations

• INSERT: Insert new data
• UPDATE: update the original data
• DELETE: Delete unnecessary data

2.3 Data in Management Table-2

■ Want to insert a new data record in the data table

UPDATE 表名 SET 字段名1=值1[,字段名2=值2]WHERE 条件表达式

mysql> update auth.users set user_passwd=password('123456') where user_name='lisi';
Query OK, 0 rows affected, 1 warning (0.00 sec)
Rows matched: 0  Changed: 0  Warnings: 1
mysql> flush privileges;  ### 刷新下

mysql> update mysql.user set authentication_string=PASSWORD('123456') where user='root';
Query OK, 0 rows affected, 1 warning (0.00 sec)
Rows matched: 1  Changed: 0  Warnings: 1
mysql> flush privileges;  ### 刷新下

2.3 Data in Management Table-3

■ Delete the specified data record in the data table

DELETE FROM 表名 WHERE 条件表达式

mysql> delete from auth.users where user_name='lisi';
Query OK, 0 rows affected (0.01 sec)

■ A statement without where conditions means to delete all records in the table

mysql> delete from auth.users;
Query OK, 0 rows affected (0.00 sec)
###不带where子句时需谨慎操作

2.4 Data in Management Table-4

■ DQL is a data query statement, only SELECT
■ It is used to find data records that meet the conditions from the data table
■ You can query without specifying conditions

SELECT 字段名1，字段名2.....FROM 表名

mysql> select * from auth.users;
+-----------+-------------------------------------------+
| user_name | user_passwd                               |
+-----------+-------------------------------------------+
| lisi      | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 |
| wangwu    | *E710DC2512FCF6F18FE0D652B53290DCB11F3334 |
+-----------+-------------------------------------------+
2 rows in set (0.00 sec)

2.5 Data in the management table-5

SELECT 字段名1，字段名2......FROM 表名 WHERE 条件表达式

mysql> select user_name,user_passwd from kk.KK where user_name='lisi'; 
+-----------+-------------------------------------------+
| user_name | user_passwd                               |
+-----------+-------------------------------------------+
| lisi      | *6BB4837EB74329105EE4568DDA7DC67ED2CA2AD9 |
+-----------+-------------------------------------------+
1 row in set (0.00 sec)

2.5 Advanced Database Operation-1

■ Empty table

• DELETE FROM tablename
• TRUNCATE TABLE tablename

mysql> truncate table tmp;

2.6 Advanced Database Operation-2

■ Temporary table

• Temporarily created table, used to save some temporary data, will not exist for a long time

在这里插入代码片

2.7 Advanced Database Operation-3

■ Clone table

• LIKE method

mysql> create table test like mytmp;
mysql> insert into test select * from mytmp;

• SHOW CREATE TABLE method

mysql> show create table mytmp\G
mysql> create table test(......);
mysql> insert into test select * from mytmp;

Three, database user authorization

3.1 Database user authorization-1

■ DCL statement to set user permissions (when the user does not exist, create a new user)

GRANT 权限列表 ON 数据库名 TO 用户名@来源地址 [IDENTIFIED BY '密码']

mysql> GRANT select ON auth.* TO 'xiaoqi'@'localhost' IDENTIFIED BY '123456';
Query OK, 0 rows affected, 1 warning (0.00 sec)

3.2 Database user authorization-2

■ View user permissions

SHOW GRANTS FOR 用户名@来源地址

mysql> SHOW GRANTS FOR 'lisi'@'20.0.0.6';

■ Revoke user permissions

REVOKE 权限列表 ON 数据库名.表名 FROM 用户名@来源地址

mysql>  REVOKE all ON auth.* FROM 'xiaoqi'@'localhost';