如果sql文件导入有问题可以执行以下语句

CREATE database activitysystem;

use activitysystem;

CREATE TABLE `user` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`user_name` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`nickname` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`password` varchar(255)  COLLATE  utf8_unicode_ci  DEFAULT NULL,
`register_date` datetime DEFAULT NULL,
`sex` char(1) COLLATE utf8_unicode_ci DEFAULT NULL,
`phone_num` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL, PRIMARY KEY (`id`)
);

CREATE TABLE `activity` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`act_name` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`act_picture` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`sponsor` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`co_organizer` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
`sign_up_start_date` datetime DEFAULT NULL,
`sign_up_end_date` datetime DEFAULT NULL,
`act_start_date` datetime DEFAULT NULL,
`act_end_date` datetime DEFAULT NULL,
`act_content` text COLLATE utf8_unicode_ci, PRIMARY KEY (`id`)
);	

CREATE TABLE `activity_sign_up` (
`user_id` int(11) NOT NULL DEFAULT '0',
`activity_id` int(11) NOT NULL DEFAULT '0',
`sign_up_time` datetime DEFAULT NULL, PRIMARY KEY (`user_id`,`activity_id`), KEY `activity_id` (`activity_id`),
CONSTRAINT `activity_sign_up_ibfk_1` FOREIGN KEY (`user_id`) REFERENCES `user` (`id`) on delete cascade on update cascade, 
CONSTRAINT `activity_sign_up_ibfk_2` FOREIGN KEY (`activity_id`) REFERENCES `activity`(`id`) on delete cascade on update cascade
);

CREATE TABLE `activity_sign_in` (
`user_id` int(11) NOT NULL DEFAULT '0',
`activity_id` int(11) NOT NULL DEFAULT '0',
`sign_in_time` datetime DEFAULT NULL, PRIMARY KEY (`user_id`,`activity_id`), KEY `activity_id` (`activity_id`),
CONSTRAINT `activity_sign_in_ibfk_2` FOREIGN KEY (`user_id`) REFERENCES `user` (`id`) on delete cascade on update cascade, 
CONSTRAINT `activity_sign_in_ibfk_3` FOREIGN KEY (`activity_id`) REFERENCES `activity`(`id`) on delete cascade on update cascade);