1.查詢系統支援當前的時區設定：
mysql> select version();
+-----------+
| version() |
+-----------+
| 8.0.12    |
+-----------+
1 row in set (0.00 sec)
mysql> show variables like '%time_zone%';
+------------------+--------+
| Variable_name    | Value  |
+------------------+--------+
| system_time_zone | CST    |
| time_zone        | SYSTEM |
+------------------+--------+
2 rows in set (0.00 sec)

2.修改時區設定：
方法1：寫入到配置檔案需要重啟mysql例項：
[mysqld] 
default-time-zone=timezone
修改為
default-time-zone = '+8:00'


方法2：線上修改和檢視：
 
mysql> set time_zone='+8:00';
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like '%time_zone%';
+------------------+--------+
| Variable_name    | Value  |
+------------------+--------+
| system_time_zone | CST    |
| time_zone        | +08:00 |
+------------------+--------+
2 rows in set (0.01 sec)

--通過now() 檢視：
mysql> show variables like '%time_zone%';
+------------------+--------+
| Variable_name    | Value  |
+------------------+--------+
| system_time_zone | CST    |
| time_zone        | +08:00 |
+------------------+--------+
2 rows in set (0.01 sec)

mysql> select now();
+---------------------+
| now()               |
+---------------------+
| 2018-08-28 16:08:38 |
+---------------------+
1 row in set (0.00 sec)

mysql> set time_zone='+0:00';
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like '%time_zone%';
+------------------+--------+
| Variable_name    | Value  |
+------------------+--------+
| system_time_zone | CST    |
| time_zone        | +00:00 |
+------------------+--------+
2 rows in set (0.01 sec)

mysql> select now();
+---------------------+
| now()               |
+---------------------+
| 2018-08-28 08:09:12 |
+---------------------+
1 row in set (0.00 sec)

--自MySQL 8.0 GA版本開始支援將引數寫入並且持久化：
mysql> set persist time_zone='+0:00';

--針對application 可以設定：
jdbc:mysql://localhost:3306/database?useUnicode=true&characterEncoding=UTF-8&useOldAliasMetadataBehavior=true&autoReconnect=true&serverTimezone=UTC 

--結論：

mysql> set time_zone='+8:00'; 和time_zone='system'是等同的，預設為系統時間。