PHP简单留言本功能实现代码

<?php
$link = mysql_connect("localhost","root"," ");
mysql_select_db("guestbook");
mysql_query("set names utf-8");
if(!$link){
 die("Connection failed: " . mysqli_connect_error());
}
 //echo "链接成功";
 
?>

<?php
 error_reporting(0);    　　　　　　　　　　　　　　　　　　　　　　//关闭NOTICE提示
 require_once "conn.php";
 $title = $_REQUEST['title'];
 $username = $_REQUEST['username'];
 $content = $_REQUEST['content'];
 $content = str_replace("\n","<br>",str_replace(" "," ",$content)); //显示'空格'和'回车'
 $week = '星期'.mb_substr( "日一二三四五六",date("w"),1,"utf-8" );
　　　　$isok =mysql_query("insert into guestlist(title,username,content,addtime)values('$title','$username','$content','".date("Y-m-d H:i:s")." $week ')"); 
 if($isok)
  {
    echo "<script>
      alert('提交成功');
     location.href='index.php';
     </script>"; 
  }else {
    echo "<script>
      alert('提交失败');
     location.href='index.php';
     </script>";
  } 
?>

body{margin:0;padding:0;}
ul,li{list-style: none;margin:0;padding:0;}
a{text-decoration: none;}
.content{
 width:800px;
 
 margin:0 auto;
 
}
.bt{
 width:799px;
 height:20px;
 text-align: center;
 background:#EB9316;
 margin:0 0 5px 0;
}
.bt>li{
 float:left;
 width:265px;
 height:20px;
 text-align: center;
 line-height: 20px;
 font-size:13px;
 
}
.nr{
 float:left; 　　　　　　　　 /*如果不浮动 后面的lynr会受影响*/
 width:799px;
 height:20px;
 text-align: center;
 background:#B9DEF0;
}
.nr>li{
 float:left;
 width:265px;
 height:20px;
 text-align: center;
 line-height: 20px;
 font-size:13px;
 
}
.lynr{
 float:left;    /*如果不浮动会 布局会乱*/
 width:800px;
 margin:1px 0 1px 0;
 
}
.content p{
 width:70px;
 height:50px;
 float:left;
 
 
}
.content span{
 display: block;
 width:710px;
 float:left;
 
 
}

td{
 width:80px;
 padding:5px 0;
 /*border: 1px solid #79ABFE;*/
 }
td input,textarea{
 border: 1px solid #79ABFE;
}
/*tr{
 display:block;　　　　　　 /*将tr设置为块体元素 显示块状后 就将其包围住了 不是一个矩形了
 
 }*/