Obsidian-Main/04. Programming/DB/MySQL.md

## Install MySQL
- 下載MySQL： https://downloads.mysql.com/archives/installer/
- 安裝
- 安裝之後，執行MSQL Installer - Community
    - ![[Pasted image 20210423152623.png]]
- 選擇MySQL Server的Reconfigure
    - ![[Pasted image 20210423152747.png]]
- 依序設定port、帳號密碼。

## Install MariaDB
1. `sudo apt install mariadb-server`
2. Configuring MariaDB: `sudo mysql_secure_installation`
    這步驟會問幾個問題，大概是：
    1.　輸入目前root的密碼
    2.　是否要切換為unix_socket？ -> No
    3.　要變更root的密碼嗎？-> No
3. Testing MariaDB: `sudo systemctl status mariadb`
4. Show version: `sudo mysqladmin version`

## Syntax
### Basic
login as root: `mysql -u root -p`

### User management
#### Create user
```sql
CREATE USER 'testuser'@'localhost' IDENTIFIED BY 'test123test!';
```

#### Remove user
```sql
DROP USER 'testuser'@'localhost';
```

#### Grant user's permission
Below commands grant user's permission to *CREATE* and *DROP*.
```sql
GRANT CREATE ON *.* TO 'testuser'@'localhost';
GRANT DROP ON tutorial_database.* TO 'testuser'@'localhost';
FLUSH PRIVILEGES;
```

#### Remove user's permission
```sql
REVOKE <permission> ON database.table FROM 'user'@'localhost';
```
上面命令中的`<permission>`必須替換成下面的其中一個：
- ALL - Allow complete access to a specific database. If a database is not specified, then allow complete access to the entirety of MySQL.
- CREATE - Allow a user to create databases and tables.
- DELETE - Allow a user to delete rows from a table.
- DROP - Allow a user to drop databases and tables.
- EXECUTE - Allow a user to execute stored routines.
- GRANT OPTION - Allow a user to grant or remove another user's privileges.
- INSERT - Allow a user to insert rows from a table.
- SELECT - Allow a user to select data from a database.
- SHOW DATABASES- Allow a user to view a list of all databases.
- UPDATE - Allow a user to update rows in a table.

例如：`REVOKE CREATE ON *.* FROM 'testuser'@'localhost';`
最後，不要忘記`FLUSH PRIVILEGES;`

#### Show user's permission
```sql
SHOW GRANTS FOR 'testuser'@'localhost';
```

#### Change user's password
```sql
ALTER USER 'user-name'@'localhost' IDENTIFIED BY 'NEW_USER_PASSWORD';
```

#### View all users
```sql
SELECT User,Host FROM mysql.user;
```

### Database
#### Show all databases
```sql
SHOW DATABASES;
```

### Create table
The rule:
```sql
CREATE TABLE table_name (column_name column_type);
```

Example:
```sql
CREATE TABLE tutorials_tbl(
   tutorial_id INT NOT NULL AUTO_INCREMENT,
   tutorial_title VARCHAR(100) NOT NULL,
   tutorial_author VARCHAR(40) NOT NULL,
   submission_date DATE,
   PRIMARY KEY ( tutorial_id )
);
```

```sql
use autostation;
CREATE TABLE station_state(
   id CHAR(255) NOT NULL,
   ip CHAR(255) NOT NULL,
   dhcp_ip CHAR(255) NOT NULL,
   name CHAR(255) NOT NULL,
   setupfilemd5 CHAR(255) NOT NULL,
   setupfileversion CHAR(255) NOT NULL,
   status CHAR(255) NOT NULL,
   update_time DATETIME NOT NULL,
   PRIMARY KEY ( id )
);
```

### Insert
The rule:
```
INSERT INTO <table_name> ( field1, field2,...fieldN )
                         VALUES
                         ( value1, value2,...valueN );
```

Example:
```
INSERT INTO client_state ( field1, field2,...fieldN )
                         VALUES
                         ( value1, value2,...valueN );
```

## 參考
-　[Create a MySQL User on Linux via Command Line | Liquid Web](https://www.liquidweb.com/kb/create-a-mysql-user-on-linux-via-command-line/)
-　[Grant Permissions to a MySQL User on Linux via Command Line | Liquid Web](https://www.liquidweb.com/kb/grant-permissions-to-a-mysql-user-on-linux-via-command-line/)
-　[Remove Permissions for a MySQL User on Linux via Command Line - Liquid Web](https://www.liquidweb.com/kb/remove-permissions-for-a-mysql-user-on-linux-via-command-line/)
-　[Remove a MySQL User on Linux via Command Line - Liquid Web](https://www.liquidweb.com/kb/remove-a-mysql-user-on-linux-via-command-line/)