資料，資料，命根就在資料 ! 操作資料庫時，一定要謹慎小心。師萬物 的程式碼看看就好，要有自己的判斷。遇到抉擇，要不恥上下問。

example

stu@Ubuntu:~$ mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 40
Server version: 8.0.12 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> use employees;
Reading table information for completion of
 
 table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> describe salaries;
+-----------+---------+------+-----+---------+-------+
| Field     | Type    | Null | Key | Default | Extra |
+-----------+---------+------+-----+---------+-------+
|
 
 emp_no    | int(11) | NO   | PRI | NULL    |       |
| salary    | int(11) | NO   |     | NULL    |       |
| from_date | date    | NO   | PRI | NULL    |       |
| to_date   | date    | NO   |     | NULL    |       |
+-----------+---------+------+-----+---------+-------+
4 rows in set (0.00 sec)

mysql> select sum(salary) from salaries;
+--------------+
| sum(salary)  |
+--------------+
| 181480757419 |
+--------------+
1 row in set (0.64 sec)

mysql> exit
Bye
stu@Ubuntu:~$ 

resource

MySQL是一個關係型資料庫管理系統，目前是開源的(2018-10)。
許可權明確，引擎與字符集等選擇恰當，命名規範。
MariaDB，Redis，MongoDB，PostgreSQL，Hive，HBase等，多作了解，拓寬心量。
Workbench，phpMyAdmin，Navicat等圖形化管理工具，豫兮若冬涉川。