ubuntu 16.04系统wordpress-4.9.4修改表引擎报告错误“Invalid default value for 'comment_date'”

最近在捣鼓wordpress主从同步的时候（ubuntu 16.04配置MySQL主从同步），需要把wp_comments的数据库引擎从MyISAM切换到INNODB（MyISAM不支持主从同步）。

在执行

$ mysql -u root -p -e "use wordpress; ALTER TABLE wp_comments ENGINE=INNODB;"

的时候报告错误：

Invalid default value for 'comment_date'

原因出在类似这样的建表语句

DROP TABLE IF EXISTS `wp_comments`;
CREATE TABLE `wp_comments`  (
  `comment_ID` bigint(20) UNSIGNED NOT NULL AUTO_INCREMENT,
  `comment_post_ID` bigint(20) UNSIGNED NOT NULL DEFAULT 0,
  `comment_author` tinytext CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_520_ci NOT NULL,
  `comment_author_email` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_520_ci NOT NULL DEFAULT '',
  `comment_author_url` varchar(200) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_520_ci NOT NULL DEFAULT '',
  `comment_author_IP` varchar(100) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_520_ci NOT NULL DEFAULT '',
  `comment_date` datetime(0) NOT NULL DEFAULT '0000-00-00 00:00:00',
  `comment_date_gmt` datetime(0) NOT NULL DEFAULT '0000-00-00 00:00:00',
  `comment_content` text CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_520_ci NOT NULL,
  `comment_karma` int(11) NOT NULL DEFAULT 0,
  `comment_approved` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_520_ci NOT NULL DEFAULT '1',
  `comment_agent` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_520_ci NOT NULL DEFAULT '',
  `comment_type` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_520_ci NOT NULL DEFAULT '',
  `comment_parent` bigint(20) UNSIGNED NOT NULL DEFAULT 0,
  `user_id` bigint(20) UNSIGNED NOT NULL DEFAULT 0,
  PRIMARY KEY (`comment_ID`) USING BTREE,
  INDEX `comment_post_ID`(`comment_post_ID`) USING BTREE,
  INDEX `comment_approved_date_gmt`(`comment_approved`, `comment_date_gmt`) USING BTREE,
  INDEX `comment_date_gmt`(`comment_date_gmt`) USING BTREE,
  INDEX `comment_parent`(`comment_parent`) USING BTREE,
  INDEX `comment_author_email`(`comment_author_email`(10)) USING BTREE
) ENGINE = MyISAM AUTO_INCREMENT = 35 CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_520_ci ROW_FORMAT = Dynamic;

这种报错多是mysql升级到5.7而引起的默认值不兼容的问题。看看你的字段名是什么，我的是时间字段，类型是datetime。想到可能是类型的默认值被限制了，查看sql_mode。果然：NO_ZERO_IN_DATE,NO_ZERO_DATE这两个参数限制时间不能为0。

可以使用如下语句查看建表命令：

$ mysql -u root -p -e "use wordpress;show create table wp_comments\G;“

注意上面的

`comment_date` datetime(0) NOT NULL DEFAULT '0000-00-00 00:00:00', 
`comment_date_gmt` datetime(0) NOT NULL DEFAULT '0000-00-00 00:00:00',

这两句受到NO_ZERO_IN_DATE,NO_ZERO_DATE的影响。

查看 sql_mode

mysql> show variables like 'sql_mode';
+---------------+-------------------------------------------------------------------------------------------------------------------------------------------+
| Variable_name | Value |
+---------------+-------------------------------------------------------------------------------------------------------------------------------------------+
| sql_mode | ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION |
+---------------+-------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql>

临时修改：

mysql> set session
 -> sql_mode='ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql>

永久修改：

修改配置文件

$ sudo vim /etc/mysql/mysql.conf.d/mysqld.cnf

在[mysqld]下面添加如下列：

sql_mode=ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION

参考链接

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导入数据库时报错1067 – Invalid default value for ‘字段名’