//创建表create table user(   tutorial_id INT NOT NULL AUTO_INCREMENT,   tutorial_title VARCHAR(100) NOT NULL,   tutorial_author VARCHAR(40) NOT NULL,   submission_date DATE,   PRIMARY KEY ( tutorial_id ));Query OK, 0 rows affected (0.61 sec) //创建banner表create table banner(   id INT NOT NULL AUTO_INCREMENT,   img_url varchar(255)  NOT NULL,   web_url text  NOT NULL,   addtime datetime,   PRIMARY KEY ( id )); //创建表3create table room(  `uid` int(11) COMMENT '用户ID',  `subject` varchar(50) CHARACTER SET utf8mb4 DEFAULT NULL COMMENT '房间标题',  `praise_num` int(20) DEFAULT '0' COMMENT '点赞数',  `gold_num` int(20) DEFAULT '0' COMMENT '本直播获得贝壳数',  `watch_num` int(11) DEFAULT '0' COMMENT '观看次数',  `review_url` varchar(200) COLLATE utf8mb4_unicode_ci DEFAULT NULL COMMENT '回放地址URL',  `addtime` timestamp NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',  `endtime` timestamp NULL DEFAULT NULL COMMENT '结束时间',   PRIMARY KEY ( uid ));//删除表DROP TABLE user;