使用mysqli实现curd

CREATE TABLE `sky_guest` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `title` varchar(50) DEFAULT '' COMMENT '主题',
  `userid` int(10) unsigned NOT NULL DEFAULT '0' COMMENT '用户id',
  `catid` tinyint(4) unsigned NOT NULL DEFAULT '0' COMMENT '类型',
  `status` tinyint(1) unsigned NOT NULL DEFAULT '0' COMMENT '状态',
  `telephone` varchar(15) NOT NULL DEFAULT '',
  `email` varchar(50) NOT NULL DEFAULT '' COMMENT '邮箱',
  `qq` varchar(15) NOT NULL DEFAULT '' COMMENT 'QQ',
  `createtime` datetime NOT NULL DEFAULT '2019-01-17 08:08:01' COMMENT '留言时间',
  `content` text COMMENT '留言内容',
  `reply_content` text COMMENT '回复内容',
  `reply_time` datetime NOT NULL DEFAULT '2019-01-17 08:08:01' COMMENT '回复时间',
  `nickname` varchar(16) NOT NULL DEFAULT '',
  `money` decimal(33,6) unsigned NOT NULL DEFAULT '0.000000',
  PRIMARY KEY (`id`),
  KEY `catid` (`catid`),
  KEY `userid` (`userid`,`id`) USING BTREE
) ENGINE=MyISAM AUTO_INCREMENT=57 DEFAULT CHARSET=utf8 COMMENT='留言板';

insert into guest set title='这是标题',content='这是内容',nickname='昵称'

update guest set title='这是修改过的标签' where id=2

delete from guest where id=1 

select id,title,content from guest limit 10
select * from guest where id=2

class mysqli{
  
}

//数据库连接
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
//数据库连接错误号码
$mysqli->connect_errno
//数据库连接错误内容
$mysqli->connect_error
//设置编码
$mysqli->set_charset("utf8mb4")) 
//执行sql语句
$result=$mysqli->query($sql);
//设置结果类型 返回一行的数据
//MYSQLI_ASSOC, MYSQLI_NUM, or MYSQLI_BOTH. 
 $result->fetch_array(MYSQLI_NUM);
 $list=array();
 while($rs=$result->fetch_arrray(MYSQLI_ASSOC)){
   $list[]=$rs;
 }
 //执行sql错误内容
$mysqli->error
//关闭连接
$mysqli->close();
//结果记录数
$result->num_rows
//关闭结果
$result->close();