php访问mysql

<?php
$dbhost='localhost';
$dbuser='root';
$dbpass='123456';
$dbname='products';
$connect=mysql_connect($dbhost,$dbuser,$dbpass);
if(!$connect) exit('数据库连接失败！');
mysql_select_db($dbname,$connect);
mysql_query('set names utf8');
//查询
$sql="SELECT * FROM `category`";
$result=mysql_query($sql);
while($row=mysql_fetch_array($result)){
 echo $row['id'];
}
//插入
$sql="INSERT INTO `category` (`id`,`name`) VALUES (NULL,'".$name."')";
$result=mysql_query($sql);
if(mysql_affected_rows()){
 echo '插入成功，插入ID为：',mysql_insert_id();
}else{
 echo '插入失败：',mysql_error();
}
//修改
$sql="UPDATE `category` SET `name`='".$name."' WHERE `id`='".$id."'";
$result=mysql_query($sql);
if(mysql_affected_rows()){
 echo '修改成功！';
}
//删除
$sql="DELETE FROM `category` WHERE `id`='".$id."'";
$result=mysql_query($sql);
if(mysql_affected_rows()){
 echo '删除成功！';
}
//关闭连接
mysql_close($connect);