之前将mysql的数据版本从5.6升级到了5.7，导入备份的数据库的时候，若时间的默认值为零会报错Error : Invalid default value for comment_date 。后来有从5.7升级到了8.0，同样有这个问题。
做了记录以备之后遇到。
5.6->5.7
root@localhost:~# mysql -u root -pEnter password:Welcome to the MySQL monitor. Commands end with ; or \g.Your MySQL connection id is 14624Server version: 5.7.30-0ubuntu0.16.04.1 (Ubuntu)Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> set global -> ;Query OK, 0 rows affected, 1 warning (0.00 sec)mysql> commit;Query OK, 0 rows affected (0.00 sec)mysql> exit;root@localhost:~#5.7->8.0 服务器系统是Debian，同时使用了Docker。
root@localhost:~# docker exec -it db mysql -u root -pEnter password:Welcome to the MySQL monitor. Commands end with ; or \g.Your MySQL connection id is 471Server version: 8.0.27 MySQL Community Server - GPLCopyright (c) 2000, 2021, Oracle and/or its affiliates.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> set global -> ;Query OK, 0 rows affected, 1 warning (0.06 sec)mysql> exit;root@localhost:~#完成之后再重建数据库，就能导入了。